I'm on a low end computer. I made 8 seasons videos on my youtube channel, there you can see for yourself (quality might be slightly compressed by youtube though, looks better on my monitor.
My computer has integrated vid card with no extra ram. The harddisc was 98% full when I recorded those videos, and I was probably running a handful programs in the background like I normally do, including 2 web browsers with about 15 open tabs. I have all the EPs installed + a handful GPs/SPs.
I'm more than happy with the graphics, it could be a little choppy but now that I cleared my harddisc that's no longer an issue. So I'd say if your computer is not too old (mine is cheap, and 3-4 years old), and there is free disc space, you should do fine.