Which OS is better

I just bought my new computer without any OS installed on it as I want to install it by myself. I am stucked with the OS part. Can anyone help me which OS is better for my new rig? XP/Vista 32 bit/64 bit and explain me why? I do have 4 GB of RAM.

I am asking so because I have read that the 64 bit versions sometimes have driver issues, software compatibility issues and many more. Also people says that Vista has too many bugs. Is that true? Do they really have trouble?

For me, its windows xp 32 bit but that is not good for future end gaming for directx 10 compatible games.

I would recommend XP 64 bit because I am using it and it don't have any compatibility issues and not even any bugs like Vista (what I feel). I play more games (mostly high end) and had never faced any issues.