I would probably suggest PPS LLR as they would be short WUs and you are only using a 32bit OS. However, I really urge you to try out Wubi. You would be able to use the 64bit capabilities of your CPU by installing this program. It would be just as if you installed a program under windows. (But you would have to reboot to use the 64bit Linux OS.) Keep in mind that 32bit vs 64 bit makes no difference for LLR work units but 64bit is faster for processing Sieve work units and thus more credit earned. Also, LLR WUs will generally make your CPU run hotter than if you choose Sieve WUs. If you choose to use your Windows 32bit OS, I would stick with LLR sub-projects. If you go with Wubi, Sieve sub-projects would be better credit wise but the final decision is yours.
32 bit OS with 64 bit CPU
This is for those who are "driving with the hand brake active" (running a 32 bit OS on a 64 bit machine) ;) wubi is a very nice tool that installs Ubuntu as a dual boot to your 64 bit machine. It's as simple as adding a program to Windows. You can even uninstall it like you would any other program. :)
After getting 64 bit OS running on your machine, here's a link to ALL BOINC clients (including Linux x64): http://boinc.berkeley.edu/download_all.php If you are new to Linux and need help getting set up, let us know.
It really is simple. :)
Ubuntu has a power save feature that throttles the CPU frequency down to save power. It does not treat BOINC as an active program so will throttle down thus causing under-performance. For those downloading the latest Ubuntu 10.04 (http://www.ubuntu.com/), please follow these directions to make sure the frequency is not throttled down while BOINC is running:
1. In Ubuntu, right click the top menu bar
2. Select add to panel
3. Select "CPU Frequency Scaling Monitor"
4. Click add
This will add a processor icon to the top menu. Click on the icon and set to "Performance". This also allows you to see the CPU frequency.
wubi - Ubuntu Installer