Apparently the HD Fury can convert HDMI/DVI/HDCP output to component video in HD. I have found it on eBay for about £80 - significantly less than buying a new TV.
You might need to buy a couple if you want to attach more than one HD source, though. For instance my TV has two Component Video input sets, plus VGA, SCART and SVideo. Only VGA and Component are HDTV compliant (maybe SCART as well, haven't checked), but an external HDCP convert is required, which the HD-Fury provides.
I'm going to need at least one for now, and another if I update to Virgin HD (although I think Component will be sufficient for Virgin at the moment, as it has Component outputs.)