Is the XBOX 360 4GB enough memory?

No… You will need an external hard drive if you get the 4gb
if your only playing those 2 games its not worth buying

Go get a refurb 360 slim with a 250 GB HDD from gamestop. You want a HDD period. The slim has the 5.1 audio toslink connection the E removed to make it cheaper.

I wouldn't get that. By the way doesn't really matter when you decide to play that would or would not take up space.

Either way, get the 250GB model.

Well I got two xbox 360 one 4gb and one 250gb ( with hard drive) and I find the 250gb better. My 4gb is slower than my 250gb in my 250gb I can keep on longer with out having to stop to take a brake and let it cool off. So I would get the Xbox 360 250gb. I like it because of its speed I hate waiting for games to load