HP Pavilion 4535

I have a HP Pavilion computer model 4535 with Win.ME. It has only 64 MB of memory, a 400 mhz processor (celeron), 6.44 gigs of usable hrd drive capacity with 1.43 gigs of free space. Could I take the memory modules (2- 128MB) out of my old MPC and put them in my HP to get 256MB? What kind of video card should I put in, because all I get are choppy video streams right now? Any other suggestions would be appreciated.