16MB is nowhere near enough. You are talking about an operating system that
is extremely graphics intensive before you even consider playing games on
it. To run XP minimally, you need at least 32MB and ideally you need 64MB.
If these games are graphics intensive, you probably need to consider a card
with 128MB and base system requirements of 256MB of ram for the main system
You might try turning off all system graphics and see if you have any better
luck though even with the setup configured for best performance, I doubt a
16MB card will provide much help. Open Control Panel, open the System
Applet, go to the Advanced tab, click Settings under performance and select
"Adjust for best performance" and click apply and ok. This will turn off a
lot of the system graphics and MAY help but given the underlying
requirements of XP, it probably won't be enough. Nonetheless, it's worth a
try, if it works even in a limited fashion, it's still an issue with the
graphics card memory.