From my experience, HP ProLiant servers are quite good value for the buck, although it’s quite a lot of buck, actually, and the tag "server" is really only applicable to the machines greater than a ML150.
The configuration and maintenance software is usable and doesn’t make management too hard.
I’m using 412645-B21 (ProLiant ML350 G5), 436013-L21 (E5345, Intel Quad-Core Xeon), 351580-B21 (E200 128MB BBWC) and 395473-B21 (500GB 7.2k HP SATA), theoretically a dream machine, but as so often with my hardware choices, a recipe for disaster.
You don’t want to use the E200 RAID controller: https://forums12.itrc.hp.com/service/forums/questionanswer.do?threadId=1154084
It is a horrible experience getting the HP service to analyze and acknowledge such an issue. Their strategy:
1. Blame the customer
1a. It’s a software issue. The customer uses uncertified applications, wrong drivers, old firmware.
1b. It’s a customer configuration issue. The customer uses uncertified parts.
2. Replace the hell out of the machine
2a. Replace disks.
2b. Replace the controller.
They’d save a ton of cash assuming a firmware problem in the first place. Especially when so many people over such a long time encounter identical issues.