Why does my system lag so bad when I use two monitors?

[Farleito]

I'm a bit hesitant from installing 64-bit because I've been told there is very, very little difference (unless you have > 4GB RAM) and it could only potentially cause problems.

If you aren't going to run > 4G, then yeah, 64 might not be worth it.

You need to be very careful here. It depends on your system configuration. If you have two 512MB videocards, that is eating up 1GB of your physical address space. The rest of your hardware (i.e. PCI devices, NICs, Soundcard, I/O controllers, bridges etc) is also taking up some physical address space. What am I getting at? If you have 4GB of RAM, you can only use ~2GB of it in 32-bit Windows, unless you use Physical Address Extensions (which is crap). In this case, you would need to use 64-bit Windows.

My point: Having more than 4MB of RAM is not the only case where you would need a 64-bit version of the OS.