I bought my first Discovery 2 a couple of months back - year 2000 and it has 105,000 miles on it and full landrover service history.
My views from research and as another newbee are that the Disco 2 is a good buy. They are less prone to rust in the boot and rear arches than the Disco 1 but still check everywhere.
In particular I suggest you look for:
1) Rust in bodywork particularly rear boot and cills - check the carpet all over for damp. The sunroofs are notorious for leaks. The rubber seals harden, the joint between the plastic sunroof frame and the metal roof is factory sealed with mastic and that hardens and fails with age and the sunroof was designed to catch water passing the rubber seal and then pipes it out via rubber hoses hidden behind the headlining and bodywork. The area where the pipes join to the plastic drip tray which in turn is mastic sealed (plastic to metal) fails and voila another leakage source. All of this is hidden from view behind the headlining.
Tell tale signs of problems will be wet headling, or stains on the headlining, wet carpets in front footwells and rear load area, sunroof handles removed, or fuses taken out on electric roofs to conceal the roofs have been stuck shut with mastic etc.
If you search this forum and google you will find the best method of fixing this problem and although it involves stripping the headlining and much interior out it is a fairly easy job with patience on a nice sunny day and the problem can be fixed. The longer part is drying out the interior!
2) Good service history in particular usual oil and filter changes and look for leaks on the drive where it has been parked.
3) If 7 seater with air rear suspension make sure the car has not sagged at the back and sits level. Air suspension bags are replaceable as diy but cost a fair few bob.
4) Check that it also runs up to mid range temperature. Mine doesn't so I am about to change th water temp stat. Not expensive but a little awkward to access so worth negotiating on. My wife prefers warm air heating!
I also chose the auto because it works well with the TD5 engine is relaxing and for someone who tows occassionally rather than regularly it copes fine and avoids the input shaft wear problems of the manual.
Mine is a TD5 GS 7 seater. The kids and dog love the 7 seats. I love the pulling power when shifting tractors and other heavy plant and it drives very well in my case with the ACE active corner suspension system.
Good luck. If you have decent car maintenance skills don't be put off by the reliability reports. If you buy a good one they are great vehciles and can be fixed using online help and tips without recourse to landrover dealers and their prices!
Jer