If you post something that is more or less a "release" package, then there are many people around here that will be happy to performance test it on whatever they happen to have lying around.
I can test it on two machines that I keep around for just such occasions.
One is an Intel GPU that only has generic Mobile Intel® 4 series Express Chipset drivers installed, it handles shader model 2.0 code for sure and claims to support at least some 3.0 stuff, although I have not bothered to test this. The other has a mostly burned out Radeon Mobile x1150. Both are whimpy dual cores that are running Windows 7 on only 2 gigs of RAM. If your code runs on both of these machines than you should not have too many surprises.
I don't use DirectX or XNA so these two computers will be ideal for testing for any missing dependencies that people may have, I can let you know about every issue I encounter from start to finish, so far as error messages go.
I won't snoop through it and I'll delete it all when the testing is done. I always do this when I'm finished working with other people's intellectual property.