Is there any point to having 4GB of RAM if you have 32bit windows XP?

I'm somewhat sceptical. Currently I have 2GB of very good RAM, plus a video card with 640MB of memory. I'm wondering about upping it to 4GB for the sake of Civ 5 and a few others; RAM is cheap at the moment and I could get some sticks which match my existing corsair stuff so there wouldn't be any performance gaps between the old and the new. Combined with a bit of overclocking on my E6600 core2duo it should give my system a decent boost. Or so I am gently musing.

But there's the limit on 2GB per program, and there's also the way video RAM is supposed to be counted in with standard RAM for that limit. If I added more my games wouldn't be able to use much of it, would they? They'd only gain back the relatively small fraction used by windows. Surely not worth the money?

I'm not going to switch to a different version of windows.