How to get a 1000 Mbps network using crossover cable
Don't ever use a crossover cable to connect a Gigabit device to anything unless you have some very specific and incredibly unusual reason to do so. Just use a straight through cable. Crossover cables and Gigabit NICs don't mix.
2001 was a long time ago. Modern network interfaces have auto-MDIX and don't need crossover cables. Gigabit speeds and crossover cables don't mix because Gigabit combines transmit and receive functions on the same wires.
Newer routers, hubs and switches (including some 10/100, and all 1 Gigabit or 10 Gigabit devices in practice) use auto-MDIX to automatically switch to the proper configuration once a cable is connected. The other four wires are used but are not crossed since auto-MDIX is mandatory at the higher data rates (1000BASE-T transmits and receives on all pairs simultaneously without any dedicated send/transmit pairs).
Update: Your wiring pattern is incorrect. You have A+ and A- on the blue pair and D+ and D- on the brown pair, which is fine. But you have B+ and C+ on the orange pair and C- and B- on the green pair. You have to match Ethernet signal pairs to physical wire pairs.
If the networks falls back to 100 mbit then you either
- Used a wrong cable. (You need a straight cat5E, cat6 or better cable for gigabit).
- or manually selected that speed on one of the computers.