If you get a WIN7 computer, go 64-bit and put about 8GBs of RAM in it. Always better to go 2 X 4GB, then 4 X 2GB.
Also, consider Microsoft Foundation.
When I set up my network, the advice was to go with Win7 32-bit for compatibility reasons. I am using a Brother MFC for my e-faxes. Do you think this is still a valid argument? All the systems are win7-32bit PRO and should I pick a 64bit for the new 'server' computer and throw it into the mix?
