In September, I knew I had to do something about my development environment.  The systems I had in place were causing too much "lag" in my build/test cycles. 

During my parts selection for the new development workstation, I chose the Western Digital Raptor 10K RPM drive.  Although you pay more for less space, you gain up to 30% in read/write speed.  This directly translates into faster build/test cycles. 

Here is a chart showing some testing done with the drive:
http://www.barefeats.com/hard38.html

So when considering new systems and their associated cost, also consider the time saved during the project and what that is really worth.