It'll be fine ... that "warning" is a tool Microsoft uses to make companies pay $200K/year to get it WHQL certified. Have you just tried the nVidia drivers?Im installing the software but it says it has not been tested for win xp. It is an MX 420 so its pretty old
In general you are quite right however in the specifc case of video cards, you're probably best off with the core-drivers (i.e., from nVidia, ATi, Matrox etc rather tha the OEM/card drivers).Be sure to select Windows XP and download the NEWEST drivers for your OS from the cards website. what brand made your card.