I had some mates round last Saturday, and we played 6 player LAN games from 3pm to 3am. All we played was Operation Flashpoint and Battlefield 1942. Old skool old times!

Anyway, we'll probably do it again in the next few months, so this time I want to buy up a load of copies of old second hand games that are good on the LAN.
We only really play:
Operation Flashpoint
BF 1942
Command and Conquer: Generals
Vietcong
These are tried and tested! And now I want your suggestions for old skool classics of that era (and machine spec requirement), so I can buy more cheap 2nd hand games. They've got to be old, cheap, with low machine spec requirements, that you loved to play. Any ideas?