After looking around some more, I've decided to cancel my first order.
I found a much more appealing computer on geeks.com!
This guy is a HP Compaq dc7100 Pentium 4 with 3.0GHz and 512M ram. It's listed as a Compaq with the manufacturer being Dell.
unfortunately it doesn't have a hard drive, but luckily I have one laying around from an old laptop. They're both sata, so hopefully all I need is a 2.5 - 3.5 adapter.
so the computer comes out to $89.99 and shipping is $18.00, which comes to a total of $107.99. Only $6 more than the 1.7Ghz XP Pro.
Overall I am much more impressed with geeks.com compared to used-pcs.com. When I canceled my order, I had to IM a guy using aim and ask him to cancel it for me. used-pcs.com never sent me a conformation email, and never asked me to validate my card. Not to mention shipping which was $4 more.
A seasoned overclocker warned me last night that Dells are notoriously tough to overclock, as they lock the bios and speed settings. After a quick google, I came across a method that requires I download a program called CPUFSB. If I have any troubles with a locked "Dell" compaq computer, that'll be my first step.
On a side note, I plan on getting a Stumpleupon link here. We'll see how that goes.