This is the PSU I choose for my system:
http://www.scan.co.uk/products/750w-...iet-fan-atx-v2
Some reviews on it:
http://www.pureoverclock.com/article1234.html
http://www.hardocp.com/article/2011/...ly_unit_review
http://www.hardwaresecrets.com/artic...ly-Review/1275
My PSU before this was an Enermax MODU82+ 525W which is still working in the family PC 4 years after being purchased, on the same system it was purchased for. I couldn't rate another PSU make higher than Enermax because I am using 2 of them and find them to be brilliant pieces of kit. They are quite, efficient, long lasting and often are able to survive stress tests above their rated power so are great quality.
I only really choose a PSU from 4 manufacturers: Enermax, Seasonic, Silverstone and Corsair(mainly because they used Seasonic kit, not so much any-more). For your price range (~£100) the Enermax NAXN 750W sticks out as the best in my opinion.
For
Your
Information: the maximum power rating(600W, 750W, 850W) is a useless indicator of the headroom provided by the PSU. What gives you headroom is Amps on the 12v rails and the quality of the PSU which results in stable voltage output at high load.