I just got mine a few weeks back... 4gb model... only have 3 games (forza 3, halo 3, and one of the ww2 FPS)... and I already plan to get a bigger HDD
forza3 requires you to use a gig of it if you want to play online... you can install the disc on the HDD to speed up load times if you have room on the HDD... you still have to insert the game disc but I know with how long load times are on forza 3 it may be worth it.
I got mine for $230+ tax came with the the 360 slim and the live starter pack (http://www.amazon.com/Xbox-360-Months-Messenger-Points-Starter/dp/B004CVRAFQ/ref=s... head phones, keypad, 400 points, and 12 month gold live card)... when I get to buy a new HDD they have aftermarket 250gb on amazon for $50...
also the slim 4gb is flat black so no finger prints... if that means anything to you ;-) lol
i've got mine setup with media player and tversity to stream movies and music from the computer... pretty awesome system:)
on a side note... you can buy used... but from what i've been told/read if you get used at least use gamestop or something like that the red ring made me decide to splurge for the new system