If you are pulling the files from the network the 100Mbps is very important. We went from 10Mbps to 100Mbps and our speed went from opening 3000 component assembly in 15 mins to 1 Min on SolidWorks.
Also, like Cichild mentioned, more memory will help. If you are swapping to your hard drive because you ran out of memory you might as well go to lunch.
FYI - You may already know this but I thought I would throw it out there for anybody that might not.........
I think Mbps stands for mega bytes per second. To find out what speed your network lines are at you can go under Start, Control Panel, Network Settings, and Local Network and it should show you the speed.
AS far as memory, right-click on your task bar in windows and select Task Manager and click on the Performance tab. You should be able to tell if you are swapping from there. Do not always believe the Available number that it shows. Look at the MEM Usage and if that number is higher than the amount of memory that you have on the computer than you are swapping. Also if your hard drive is doing allot of chattering this is a good sing that you are swapping. BBJT CSWP