Do I need more memory?

[Mark Phillips]

My computer has Debian testing and gnome installed. I rarely turn it off, and 
I noticed using system monitor that I have about 75% memory in use and about 
50% or my swap in use. Should I get more memory? I notice an occasional slow 
down when I have a lot of windows open and I am switching between tasks. I do 
a lot of python (zope & plone) and java (servlets) development, as well as 
openoffice documents and spreadsheets. I have 512 MB of RAM. 
-- 
Mark