My experience of Dell is that they are one of the best, and if I could afford to buy from them in all cases I would. They are however a tad more expensive. We used them in a company I worked for and never had problems getting things sorted. Also had a nice account manager who gave good quotes :)
Evesham however failed 3 times to supply a working machine for testing when we were looking to change our supplier. Even when they did get a working machine to us it had the wrong OS on it. They sent an engineer out with a replacement hard drive which should've had the correct OS. It didn't so he stayed to re-install it. Needless to say they didn't get the business.
The Dell PC's are almost silent, I don't think it should be a major concern how the cables are routed. Their flat screen monitors are also pretty nice and its very rare to have any dead pixles. Bought over 50 in one batch and didn't have one with a fault.
I have recently purchased a Dell 8300 with 17inch LCD, pentium 4 2.6ghz (hyperthread model) 512k ram, cdrom/cdrw and seperate dvd, nice graphics card (dvi to run the dvi flat panel) Win XP etc etc, also got a free printer and all came well under ?1000-hunt the web for special partner offer like free delivery or 10% off (which I got).
Delivery was very swift-just over a week from placing order. Courier took it to wrong address at wrong time-I complained to Dell (not really their fault in a way) and got delivery charge refunded next day.