PostgreSQL on Linux PC vs MacOS X

We currently are running a data intensive web service on a Mac using 4D.
The developers of our site are looking at converting this web service to
PostgreSQL. We will have a backup of our three production servers at our
location. The developers are recommending that I purchase a 2GHz Dual
Processor G5 with between 2GB and 4 GB RAM. They say that this
configuration would be able to easily run a copy of all three production
servers. My question is: has anybody had any experience comparing the
performance of PostgreSQL on a G5 Mac versus a PC running Linux? Can
anyone tell me if there are any benefits of running PostgreSQL on one
platform over the other. Anything that can help me make the best
decision would be appreciated.

--
James Strickland - MCP
IT Manager
American Roamer
901-377-8585
http://www.americanroamer.com