As FreeHAL doesn't use much CPU, it can be run in a VM and give you as much credit as running on a real PC. The project allows you to have as many VMs running as real PCs. It doesn't matter where the VMs run - you can have 3 PCs running FreeHAL, with one of the PCs running 3 VMs running FreeHal for a total of 6 FreeHAL installations.
After a bit of experimenting I found the following to be the easiest way to get a platform to run a FreeHAL VM under Windows (using both XP Home and Win 7 Home Premium 64 bit).
- Download Windows Virtual PC 2007 from http://www.microsoft.com/downloads/details.aspx?FamilyId=28C97D22-6EB8-4A09-A7F7-F6C7A1F000B5&displaylang=en (http://www.microsoft.com/downloads/details.aspx?FamilyId=28C97D22-6EB8-4A09-A7F7-F6C7A1F000B5&displaylang=en) It complained that Win XP Home and Win 7 Home Premium were not supported, but it works fine on these
- Download a Windows XP wirtual machine disk image from http://www.microsoft.com/downloads/details.aspx?FamilyID=21eabb90-958f-4b64-b5f1-73d0a413c8ef&displaylang=en (http://www.microsoft.com/downloads/details.aspx?FamilyID=21eabb90-958f-4b64-b5f1-73d0a413c8ef&displaylang=en). The IE6 version is the smallest download.
Create a VM using the image, makiing sure to set the memory to 900Mb (too much less and FreeHAL won't download the full quota of 25 tasks). Start the VM and download and install BOINC, and turn off the screen saver (if you don't want to remember the VMs password). (At this stage you can shut down the VM and copy the disk image (vhd) as a base for other VMs if you are going to have multiples, so you won't need to download and install BOINC again). Then just connect BOINC manager to FreeHAL and away you go.
As a rule of thumb allow about a GB of additional memory per VM - e.g. a 2GB XP can run one, a 3 or 4GB XP can run 2 (XP 32 bit can't see more than 3GB). 64 bit Windows with 4GB could run 3 (haven't tried this, also depends on what other stuff is running on the machine - am assuming these are pretty much dedicated crunchers).
The downside to this approach is that the VM images expire every three months, so you need to download and reconfigure/reinslall a new image each three months, and merge the old 'PCs' with the new ones once they are running so that BOINC doesn'tv think there are now twice as many VMs. You don't need to reinstall /reconfigure Windows Virtual PC - just copy the new VHD file over the existing ones.