OK I found this
so there is a Powerspec brand after all. But there's very little about the b810 on the Internet about it. There's a powerspec.com website, but unfortunately nothing about a model b810 athttp://www.powerspec.com/support/support_archive.phtml
So I guess we can't tell much about your computer from the model name and number. I was hoping we could look up whether the video card had discrete video memory or only "borrowed" memory. Dxdiag doesn't distinguish.
By the way, did the computer play all these games that aren't playing now before it was "upgraded" from XP to Windows 7? If so, maybe it's a driver issue.