We function just fine running XP with 2-3 GB where I work on about 600 computers. Fortunately we only use the comptuers for web browsing and word processing.
I think 6-8 is overkill for the average user. And from my guess this is an old computer that the OP is trying to decide if it's worth hooking up or not.
Honestly, 1GB isn't really going to be suffiecient no matter what you do. You will notice the slowness. I would recommend 2-4GB - preferebly 4 for most home users (which you can't hardly buy a new computer without 4 in it now). If it's an old computer upgrading to 2 or 3 (because it's probably not 64 bit and therefore only supports upto 3) should be enough for basic functions like web browsing.