need more info really, which games, they should all run on xp with a couple of microsoft exceptions (halo 2 etc) but they should just refuse to install.
can you post the blue screen message or location. no gaming software should force a reinstall of the operating system something sounds very wrong with the configuration, but could do with more info really.
was it prebuilt? was o/s installed, drivers? which games and exact error message or software location.
the dos theory i have not heard before.