I would not hesitate recommending a Dell. Back in 1998 I bought a Dell XPS R400 (Pentium II 400 MHz) and was able to upgrade (over the course of three years):
1. The video card
2. The sound card
3. The DVD drive
4. The RAM
5. The hard drive
I was also able to add
1. A Voodoo2 card
2. A CD-RW drive
There is something to be said for buying a pre-built Dell, and getting the service and support that comes with it. With some of the Hot Deals, it can also be more cost effective than building it yourself. Pre-built computers aren't for everyone, and for many of the power users that frequent these forums, Dells are not adequate. With a Dell you get an inexpensive computer with a number of quality parts and good service and support. You sacrifice full control over the parts that are included and some upgradeability options.