With an install rate of more than 5% on Windows PCs worldwide, uTorrent is now by far the most popular BitTorrent client. Azureus, the most installed BitTorrent application of last year fell back to the third place.

The graph on the right (click to enlarge) is based on data published by Digital Music News based on reports from PC Pitstop, a company that gathers data by “inspecting” the computers of users that try their free online virus / spyware scanners. The data used in this report are collected from Windows registry and table entries of over a million PC’s.

The percentages reflect the percentage of PCs that has these applications installed. September last year Azureus was installed on more than 3% of all PCs but their install rate has declined by more than 30% this year, while uTorrent’s install rate nearly tripled.

In the table below we have listed the 5 most installed BitTorrent applications. It is interesting to not that Azureus moved from the first to the third spot over the past year. The BitTorrent mainline client is now runner up. This means that BitTorrent Inc. now owns the two most popular BitTorrent clients.

The percentages in the table indicate the install base of the most popular BitTorrent clients:

Rank Application Installed on % Desktops 1. uTorrent 5.56% 2. BitTorrent (a.k.a. mainline) 2.28% 3. Azureus 2.11% 4. Bitcomet 1.89% 5. Bitlord 1.27%

From the data where the report is based on we further learn that Limewire’s popularity is slowly declining. However, with an install base of almost 18% it is still the P2P application that is installed on most desktop computers. Unfortunately Digital Music News has trouble interpreting their own data, they claim in their press release that it is 36.4%, but that is the market share compared to other P2P clients (shame on you!).

Apart from this tiny mistake, there are a few more concerns about the usability of the data. For example, install rates do not equal usage. The fact that someone installed a P2P client does not mean that they actually use it. So the report can’t say much about the popularity of a filesharing network or application. Secondly, it could be that Azureus and BitTorrent Mainline are installed on almost an equal number of PCs, but that the BitTorrent mainline client is hardly ever used. For instance, novices may start with the mainline client, but move on to better BitTorrent clients later on. Lastly, the report is based on a sample of people who voluntarily did an online spyware scan, something to think about.

Perhaps an even more important comment on the data collection for this report, uTorrent doesn’t necessarily use the Windows registry. So the real install rate for uTorrent might be even higher. Also, Azureus is a true multi-platform client, whilst this test is only for windows based systems.

In summing up we think it is (despite all the flaws) safe to say that uTorrent is becoming more popular while Azureus is losing ground. Whether this is due to negative factors affecting Azureus (such as the rebranding to Vuze, Java or the heavy use of resources), or positive factors around the mainline and ÂµTorrent clients (such as the small install size, and low system requirements) it certainly shows a slide for Azureus.