The processors are on par so no worries here.
I'd take a look at your hard drive. Usually 20Gb units were not that fast as newer 60-80Gb drives (not because of size, but because of platter speeds, cache optimization, and plain simple technological development along the years)
Are both hard drives connected to the same IDE line? Try connecting one to the first controller and the other to the second one, both as master.
Also, take a look at your prefecth folder in your computer. (usually on c:\windows\prefecth) it will contain names of executable files along with a short number string and a .pf extension (like FIREFOX.EXE-030B768A.pf for example) A good way to improve program loading is to do the following routine:
Clean the prefetch folder contents. Reboot the machine. Reboot it again (you need to let the machine sense the order your boot programs load) then start the programs you most usually run one by one, closing the first before running the next. After you have done this, go to Start > Run and type
%windir%\system32\rundll32.exe advapi32.dll,ProcessIdleTasks
(this has to be run on a single line)
this will record the data windows has collected about your boot-up programs and the optimized physical location info for the programs you run the most.
Now, on the same start>run... box type cmd an press Enter.
If windows is installed on the c:> drive then type
%windir%\system32\defrag.exe /b c:
If not, substitute C: for the drive letter you have installed windows into. This will optimize your boot process (windows will load faster)
after that has run, type
%windir%\system32\defrag.exe /v c:
Run this substituting the c: part with each drive letter you have. Wait for the first task to run before running the second.
By doing this, you will let windows find the best location for your programs to be on your hard drives, and then letting hem run faster.
You can also go to http://www.safer-networking.org/ and download the