I have actually purchased the computer with 4GB RAM (instead of the standard 2 GB) because I wanted to obtain experience with desktop virtualisation. Running a virtual Windows 7 within a Windows 7 with only 2.8 GB RAM appears to be pretty slow. The additional memory that the 32 bit OS would be able to use could improve my experience. I don't think I want to buy an extra video card now... BTW, Linux runs w/o any speed issue in VMplayer.
what CPU does yours have? My G555 laptop has no problems running virtual box. checkout www.tinypic.com/mrpeter1985 and you can see I can run 3 different OS's fine at the same time. Ubuntu, XP pro and Win7. So just running Win7 should not be a problem, unless your giving it too much ram. Only give it 1g of ram. I only have 3g of ram. I gave 7 1024mb of ram, XP 756mb of ram, and ubuntu 256mb of ram and still had 400mb of free ram. SO I do not know what your doing wrong. Try virtual box, and see if you still have that issue.
IT Specialist and Consultant Lenovo Tablet Evangelist Current Machines: IdeaCentre A300, and ThinkPad Tablet