PCOPTIONS has some good deals and you can mix and match to suit your pocket and/or add extra ram HDD tuner cards etc at the website before you purchase. Mine cost about £650 and included 2GB RAM 300GB HDD dual tuner Intel Duo core CPU 2.67Ghz. It sits in a nice silver and black case under the telly and lets me record and watch what and when I want. I can also stream music throughout the house through an internet radio (£49.99 from Aldi) All my CDs are now in a box in the loft the files loaded on the Media centre. Photos are next along with the wedding and little un's video.
Down side is VISTA by default but i'm getting used to it.
Hope this helps.