Virgin Media are currently offering their V+ HD PVR for an installation price of £75. Rental is £5 a month or free if you have the XL package.
From the Virgin Media Site:
"With our V+ box you can:
Pause, rewind and record live TV, so if the phone rings at a crucial moment, you can just pause the action and pick up where you left off.
Record two programmes while watching a third. No need for tapes and no hassle.
Plus it's HD-Ready if you are... "