How do I select a new/used amp for a new system?

I need advice about how to select the proper amp/pre-amp/integrated amp to use in a new system I want for my master bedroom. I want to be able to run CD's for classical/reggae/rock and DVD's for surround sound. I am NEW in high end A/V equipment and do not have speakers yet. I am amazed(!)with the sound of Linn speakers I heard at a Linn dealer and would like a similar sound either with Linn's or other's you may suggest. The distance from me to the Plasma TV is 14 feet. The room is 14x18 feet. I know the amp/power is very important and do not know how to match it (watts/channel, ohms, etc.)with whatever speakers and sub I get. Any advice would be greatly appreciated. Price range max $5,000.00 retail for the amp but will consider used equipment to save some $$. Speakers I have considered are Linn Katan, Keilidh; B & W CM1, B & M 805x; Ariel, Vienna (still investigating speaker choices). Gary