I have 850MHz Athlon, 512MB, Win XP Pro, Limewire Pro 2.3.3, Java 1.4, sharing 2000 files.

Doesn't matter if I'm an ultra peer or not, javaw.exe averages 60MB of RAM!!
The minimum is 30MB and the most I see is 70MB, but 60-65 seems to be the most common.
CPU usage is between 0 and 40% although it jumps to 100% from time to time.

--Brian