That's about it. I have to wait to replace my video card before I can try it (I'm running a very old Quadro 64 MB card since my GeForce went belly up).
My processor has 512KB L2 Cache. What do you think?
I think it's worth a try. My suggestion is to close apps that you're not currently using, rather than keep them open in the background. That will improve things a lot on a P4 with 2GB of RAM. I'd use Win7-32bit, not 64bit.
Half a MB of L2 is small these days, but not unreasonable. By way of comparison, my system is Core2 Duo T5600, 1.83 GHz, 2MB L2, 2GB RAM.
There's also a function in Win7 (under Computer -> Properties) that rates the quality of the user experience based on the hardware it sees. It would be interesting to see what it says.