The Freelander 1 is a great truck, but it has its potential issues. Window regulator cables are mild steel rather than stainless, so this is a known problem. As mentioned, the tailgate seals can leak, but this is most often due to a buildup of crud and a good clean and silicon grease will sort it. If you see a hole drilled through the storage bay floor this was done to empty it of water!
VCUs CAN fail, but it's a couple of hundred quid to replace with a reconditioned one, along with the bearings. Servicing is dead easy, although the TD4 air filter is a sod to get to. Make certain the crankcase breather filter is clean too, as Blaven mentions. The tailgate handle micro-switch can fail too, meaning you can't open the tailgate. There's no internal handle, so the only way to open it is to remove the tailgate trim from inside (I know, I've done it) and release the tailgate lock manually. HDC can have an intermittent issue if the wiring gets damaged, but as this is almost always due to someone messing about with the gear-lever gaiter it's not an inherent fault. Gearboxes have a reputation of being soft, but this is almost certainly due to service intervals being ignored.
The TD4 is the one to go for, but if you find a 1.8 petrol that's had the cylinder head gasket modification done, there's nothing to worry about. It's the same K-series engine that the Rover 214, 216, etc had, and it's a decent enough engine if looked after properly.
My 2004 Td4 went for £2k with 129k on the clock and still drove like new. That was over 4 years ago, and it's still going strong.
All in all, it's a superb truck, with seriously good off-road ability (again, I know. I've done it!)
