You mean your graphics card is 64-bit as in the GRAM interface or was that a typo and it should mean 64MB of memory? In any case, even the budget cards have 256Mb of memory, get a X300, that will handle EVERYTHING VISTA can throw at it and it can take light gaming too. Games like half life 2 run on medium with the X300, but then the Source engine is optimised for Ati cards, so that might not be a good indicator.