I'll be upgrading the GPU and adding RAM. I'm buying this from dell outlet with a 20% off cupon.
Inspiron 580
Intel Core i5-750 Processor (8MB Cache, 2.66GHz)
Genuine Windows 7 Home Premium
Inspiron Desktop 580 MiniTower
750 GB SATA II Hard Drive (7200RPM)
4 GB Dual Channel DDR3 SDRAM at 1066MHz (4 DIMMs)
16X DVD +/- RW Optical Drive
1 GB ATI Radeon HD 5450 DDR3
$415
That's not bad at all. If you're going to be upgrading the gpu, make sure that the power supply has a PCI-e port, otherwise you'll need to go with either a weaker card, or a new power supply aswell. Generally most psu's do now a days, but I'm not sure how it is with pre-builts, I've never bought one.
And in terms of ram, you shouldn't really need to upgrade, 4 gigs will be good for damn near anything you throw at it, unless you plan on going from 1066MHz to something else.
Also, I hope you know the case is going to be pretty small, but I'm assuming you've seen the actual computer.
But yeah, for that price, good find, and have fun with it. [: