It may not be. Read this post!
Lots of blah, blah (no disrespect, just LOTS of info) until reply #7 (mine), read on...
Lots of threads about hard drive that won't work in older systems (been there). Most system built before 2003 don't support hard drives over 137GB.
I couldn't find your system is search, only upgrades for RAM and stuff. You'll have to check it out yourself.