Oh, this is just WEIRD.  WMC had been working perfectly for 2 years on Freeview DVB-T, no issues at all.  A crash took out the media center database - suggestions online said to delete it, rescan channels, and it would rebuild.

Okay, no problem.

Deleted the media center database C:\ProgramData\Microsoft\eHome\mcepg1-2.db as it had become corrupted, reset windows media center, and now ALL of the freeview channels are having crappy playback.  Signal strength is 90%+ every time, NOTHING else has changed, but now I get pixelation and sound skips every 5-10 seconds, especially on TV3.

Utterly bewildered.  What settings do people use for their tv decoding on WMC 7?  Standard microsoft, or other?

Considering blowing the machine away and start again.  *nervous noises*

AJ