I work in the IT field and work with over 400 computers, 99% of them being Dell. We haven't had too many problems w/Dell and customer service has been better than any other company. So if your not a big computer user I would say go on Dell's website and find you a decent middle-ranged PC for around $500.
On another note, if you are going to be using your PC more so than before and might want to do some upgrading afterwards down the road. I would definitely check these two sites:
http://www.tigerdirect.com/ http://www.newegg.com/
I custom built my PC buying parts from the above websites (best prices anywhere, I researched for months). They have excellent customer service if any thing gets messed up or you have any problems. Also they sell Barebone kits, which might be what your lookin for since you don't need a monitor.
The main key to upgrading in the future is to basically buy a nice motherboard that has the ability to handle a bigger CPU and memory (usually what is upgraded) this will allow you to upgrade later w/out having to buy another MB, which can be expensive.
I spent a great deal on my MB and bought a cheap cpu chip that way it still works great and later when cpu prices go down I can just buy a better CPU and stick it in, that simple.
OMG, I totally forgot about this thread! 
