Digital BW, The Print

Hello - I've been dabbling in scanning and printing in B&W for a 
couple of years.  I have an Epson 5000 and recently purchased a 1280 
that I plan to use with MIS Quadtones.

I'm running Photoshop 5.5 on Windows 98 with a Pentium III 550MHz 
chip and 256MB RAM.  I plan to upgrade/rebuild my system and would 
appreciate any advice on what I should go to.  

Has anyone tried Windows XP and what are its advantages?  

Should I go Pentium 4 or AMD?  

How much RAM is ideal/sensible?

What are the advantages of Photoshop 6 vs 5.5?

Thanks in advance for your input.  I've already enjoyed reading 
previous postings.

Brad Boyd - Portland OR