Hi,
I can confirm the WD20EARS is ok as a drive.
If you want to do this then spare some time, read all you can from this forum and other sources and go for it.
I now have 2TB internal 240hrs of HD available and the old 320 external HD. Most time took was for the backup and copying of files. I first copied the old 320 HD onto my Windows 7 laptop using the Ubuntu 10.04 CD boot which sees all internal windows and external linux drives. Made some mistakes but not any unrecoverable ones. Copied all data on new drive from laptop only to find that the hdr would not recognise the drive (due to my bad format of sda3, was not linux 83.
It would be useful to have a spare sata drive as if the HDR sees a drive it thinks needs formating it will prompt to format this and will not allow you to continue untill it formats a drive. So a spare in that case is useful. In that case I let it format the old 320Gb drive having backed it up on my laptop. Risky yes but the most you can lose is your old TV data.
All in all I have all my old data available, tons of extra space and yes I can confirm the HD stuff still works. DR WHO lives in glorious HD after living on my old HD in the HDR, then my laptop, then the old HD again and finally transfered from the 320 drive via USB to the new 2TB drive.
Its useful to know what not to do as well as what to do, just in case. Most of all be patient and try not to skip any steps.
Windows 7 also now reads .TS files via the VLC software , SD fine but HD does not work as this is protected. That is BBC HD at least as I dont think I had any ITV HD recordings.
As for hardware the drive was about £100.98 and the ICY box IB-318StUS2-B esata box £31.65 both inc vat and delivery on offer last week from aria.co.uk You can buy cheaper boxes but this one works and looks nice laid flat next to the HDR.
http://www.aria.co.uk/Products/Compo...roductId=40039
Note just checked its £3 cheaper but ony 19 left.
http://www.aria.co.uk/Products/Compo...roductId=35986
Before I waffle on any more as said read all you can and go for it.