10 means 10 Megabits
100 means 100 Megabits
1000 means 1000 Megabits
The higher the better, as it's faster. However, to get any speed difference every single connection must have this speed capability. The vast majority of home and even business networks are still using 10/100 (your home broadband speed is probably about 2mbps, so 100mbps is more than fast enough). So, do what Phantaxus says and stick with 10/100.