Best thing to do is this-
Buy a Haupage HD PVR, you can pick a used one up for just over £100 on ebay and they seem to be in good condition. Brand new they are around £190-£200. Other alternatives for HD recording are more expensive and harder to use.
Buy a HIGH QUALITY HD PS3 component cable as the PVR doesn't come with this, it costs around £3.99 for a cheap one or £20 for a good one.
Then download/buy (preferably legally since these programs cost a lot) either Sony Vegas Pro if you are on a windows pc or Final Cut pro if you are on a mac. (Final cut express doesn't cut it and is a poor program)
If you are using a mac buy HDPVRCapture from here-
http://www.steventoth.net/blog/products/hdpvr-capture/
If you are using windows then the HDPVR comes with software to capture with =]