Well, I've got it running on a desktop rig with 512MB RAM, P4 3.2GHz and a GeForce FX5200.
It gets about 30FPS at 800x600, so you'll probably be all right in terms of it even starting the game. But it won't be too good, it will run, but be a bit rubbish.
It runs at approx. 90 FPS on medium/high settings at 1024x768 with the notebook specs in my sig.
I strongly recommend 1GB RAM - it really does cut the load times, it amazed me.
Conclusion - the game will run, but it won't run anything like smoothly or with good graphics. Consider yourself lucky: on some setups it won't even start up. You should really consider an all-round upgrade if you can afford it, because the gear you've got is really getting on a good bit now.
MarxSoccer has given you the system specs, work on the basis of those. (Actually, they are the minimum that EA will support via their technical people - the game will work on crappier hardware than that, I know from experience
Hope I've helped, good luck with BF2,