Presumably you use the Crystal Palace transmitter, which does not go 'digital only' until April this year.
Even if you could get the V1G working, you will only get a short period of use as it would stop forever in April 2012 so it may not be worth too much effort.
I see there is a software update for the TV Tuner on the download site here: -
http://www.sony.co.uk/support/en/product/PCV-V1_G/updates
You need the 'Sony RealTime MPEG Encoder Board Driver' which you will find under Latest Downloads -> Windows XP -> Drivers. It may be worth installing this as a last effort.
A cheap USB digital tuner could be the best way forward.
