I got a NAD C352 last week for £220 delivered. Paid slightly more for it than others on ebay but it was brand new in August 09 with a 3 year warranty. Excellent amp for the money
I would suggest looking for a Nad C352, C370 if you need even more power, Marantz PM7200, Arcam Alpha A70, Music fidelity A100 or Audiolab A8000
Mine is connected to my B&W 603 speakers and Xonar essence soundcard via cambridge arctic interconnector.
edit - I just read 'music in your office' Does your office PC have a decent soundcard, no point in spending hundreds on amp and speakers if you use onboard sound