For old timers, there's still a certain peace of mind that comes with a new install, especially on a computer that has been up and running for a while. Even if there's nothing apparently wrong with your Windows 7 installation, starting fresh can wipe out apps, settings, and other cruft that you no longer use or have simply forgotten about. There's a peace of mind in knowing you're starting with an operating system that is as clean as it can possibly be.

On the other hand, doing a clean install is a huge pain. You have to reinstall and reconfigure all of your applications, assuming you can find all of the requisite install media and product keys. You've got to track down drivers on manufacturer product pages that may or may not have even been updated with drivers for your computer. The install time you save versus doing an upgrade install will be more than wiped out by the time you spend getting everything just the way you like it.

Conventional wisdom usually says to do a clean install when upgrading your operating system, but operating systems have gotten better at dealing with upgrade installs. This charge is led by smartphones and tablets, which simplify even major updates by making them come down automatically over the Internet. We performed an upgrade install on a Windows 7 PC in daily use so we could see whether the stigma against upgrade installs is still applicable.

System requirements

Before we begin, let's double-check our system specs to make sure we're good to go. We last looked at Windows 8's system requirements during the Release Preview phase of its development, and not much has changed since then. Anything sold with Windows 7 on it should run Windows 8 just fine without substantial hardware upgrades. Anything sold during the Vista era should run fine also, as long as you've got enough memory and a sufficient graphics card.

Microsoft's official line is that any computer that can run Windows 7 is capable of running Windows 8. In our experience this is generally true: slower and older hardware will run Windows 8 and desktop applications about as well as ran Windows 7 (and performance is improved in some cases, as we'll see in our benchmarking section). Drivers developed for Windows Vista and Windows 7 will generally work in Windows 8, though the older the drivers are the higher the risk is that something will go wrong.

However, there are computers that will run Windows 8, and then there are computers that will run Windows 8 well. While an old Atom netbook will run the new operating system, its slow CPU and integrated graphics processor will likely choke on games and other graphically intense applications from the Windows Store. Additionally, there are some features that won't work unless your system has certain hardware features—there will be games that require a tablet's motion sensors, for example, and snapping Windows 8-style apps requires a screen resolution of at least 1366×768. If your screen resolution is lower than 1024×768, you won't be able to run any Metro apps at all.

Even so, you don't need cutting-edge hardware to run Windows 8 and most of its apps well. Any mainstream dual-core processor and relatively recent Direct3D 10 or 11 graphics card will give you sufficient oomph to run just about anything Windows 8 can throw at your system. RAM is also cheap enough these days that getting the minimum amount for good performance (at least 2GB for 32-bit Windows 8, and at least 4GB for 64-bit) won't set you back much if you don't already have it.

For more specific hardware recommendations, we'll provide the table from our previous article: Microsoft's minimum Windows 8 requirements are on the left, and our recommended requirements are on the right.

Component Microsoft says Ars recommends Processor 1GHz or faster Intel Core 2 Duo, AMD Athlon X2 or better Graphics DirectX 9 graphics device with WDDM 1.0 driver or better Dedicated GPU: AMD Radeon HD 2000 series, NVIDIA GeForce 8 series or better; Integrated GPU: AMD Radeon HD 3200, NVIDIA GeForce 9400, Intel HD Graphics or better RAM 1GB (32-bit) or 2GB (64-bit) 2GB (32-bit) or 4GB (64-bit) Hard Drive 160GB (32-bit) or 200GB (64-bit) Solid-state drive

Upgrade install vs. clean install

If your system is up to snuff, it's time to perform your upgrade install! First, make sure you've got a product key for an edition of Windows 8 that can upgrade your edition of Windows 7. Here's how it breaks down.

Windows 8 can be used to upgrade Windows 7 Starter, Windows 7 Home Basic, and Windows 7 Home Premium.

Windows 8 Pro can be used to upgrade Windows 7 Starter, Windows 7 Home Basic, Windows 7 Home Premium, Windows 7 Professional, and Windows 7 Ultimate.

Windows 8 Enterprise can be used to upgrade Windows 7 Professional and Windows 7 Enterprise.

Windows XP and Windows Vista users can perform upgrade installs, but only their files will be preserved. Their applications must be reinstalled.

The system we're using to test the upgrade process is a Windows machine in light but daily use. As a result, it's got a fair amount of stuff on it: the Office 2013 preview, the latest Android SDK (along with some of the hacks we used to get Jelly Bean on our Kindle Fire), iTunes and iCloud for Windows, Steam and a few games, Dropbox, Microsoft Security Essentials, a smattering of different Web browsers, and about 20GB of photos, documents, and other data. There were around 20GB free on my 64GB solid-state drive when I began the upgrade process.

The computer is configured with one password-protected local user account. There are a few tweaks to the operating system's settings: the screen locks whenever the screensaver or sleep mode is activated; the computer is connected to a wireless HP all-in-one printer; and we've configured a network bridge to allow a desk SIP phone to connect to our home network through the desktop's wireless connection.

This machine is a Sandy Bridge-based, custom-built desktop running 64-bit Windows 7 and fully up-to-date drivers and software. It represents a bit of a "best case" for many potential upgraders, whose machines will be much more bogged down with extraneous programs and settings—and many, many gigabytes of data. Still, it is used every day, and it's sufficiently "lived in" that it should be good enough to help us examine Windows 8's improved upgrade install process.

Upgrading from a DVD or USB stick

From within Windows 7, running Setup from a DVD or USB drive (either one that you purchased from a retail store or created using the downloadable installer) will launch the upgrade installer, which we'll walk you through in screenshots. Keep in mind that you can perform an upgrade install of Windows 8 from both "upgrade" and "clean install" media: