Pros Comes with 800 mhz DDR2 memory and supports up to 4 GB. Also, supports a wide variety of LGA 775 processors and PCI, AGP, and PCI-E x16 graphics cards. It also has a PCI-E x1 slot. Small form factor (Mini) but not too small to work in.
Cons The small form factor doesn't support ATX , EATX, etc. motherboards, however, mATX is fairly common. Also, there is just one PCI-E x16 slot (not a big deal). My biggest "gripe" would be that the AGP slot is in the top position instead of the PCI-Ex16
Summary This PC is a very good value for the money. You can get 4gb of ram, a decent video card, and more straight from Dell when you order it. It may not seem customizable, but in fact I replaced the power supply and video card (620W PSU and GTX 460 1GB SC) and it games just fine now. The only one thing that bothers me is the lack of information online about this system (specifically the motherboard) unless you go to Dell, but even there some of the info is hard to find. So far, this PC has served me well, and I recommend it to all those on a budget who still would like a "decent" PC.