I've never liked wholesales systems, being
1) warrany gets void if you want to add anything (like extra RAM) if you remove that sticker on the casing.
2) when parts are damaged, it takes 1 day to call them up, 1 day to arrive, 1 day to bring it back and many moons to bring it back. DIY allows me to switch the part immediately.
3) Built-in parts. DELL/HP/ACER mostly depends on on-board parts. Like VGA, sound etc. Never liked the idea of bulit in parts, CPU processing, RAM allocation all gets shared. Speed is one thing you can forget about getting from whole sale systems.
4) No upgrade path. One, two years down the road, you simply have no upgrade path, you can't change anything without dumping the entire system. Has no resale value and you have to go through the whole thing on buying a new system. AGAIN.
5) Optional changes - adds video card, sound blah blah. Costs a damn blardy bomb, a leg, an arm and probably your car.
I would advise you, find a friend, pay him a sum of money to build a system to your preference. At least 2 months down the road, you want to upgrade to another 2GB RAM, ACER/HP/DELL won't be telling you 1) system cannot support, 2) it costs $4K, 3) No parts available yet.
As for Macs, they're nice, they're cool BUT, same problem with wholesale systems, you can't upgrade the parts simply by yourself.
As for LCD, if you aren't into hardcore image editing, any LCD would suffice. CRTs are getting bulkier for my preference,
Hope it helps.