I have installed it on my eee pc 4G (900mhz celeron, 4gb hard drive, 1gb ram). I was very surprised when it ran very fast. However I only have about 300mb of hard drive space left so I can't download anything else, which is a nuisance.
There is a "lite" version of windows 7 on a forum called modmyeee.com. The finished install is only about 3.5 gb.