Does the 64-bit vs. 32-bit in graphics card matter?

I've had some graphic card woes lately...I think it's time I get a new card. My pc's fairly old, running xp, soon to be dual-booting vista as well. Both OS are 32-bit, whatever that really means. I'm searching around for an inexpensive cheap video card, and a difference. One card is 32-bit, the other is 64-bit. The 64-bit card looks all around better, but is what does that 64-bit memory or whatever really mean? Does it matter? thanks for answering and Merry Christmas