Welcome to Answerpool photolbw
I imagine you should not have any problem with resolution bar that the Monitor can handle and what Graphic card is fitted to your machine
also what version of Windows are you running?
I'm not a graphics expert
a rough estimate you will need to set the resolution to 1024 x 768 and 256 colors or (32 bit) high resolution (XP)
which is ok for most machines
If your setup is Windows 98 then Max is 800 x 800 (32 colors)
Don't use interlacing (false looking) and bad on the eyes

I posted a sticky post at the top of the Beginners forum for a a tool called Belarc which will find and display all the above if you are unsure of the setup(other way is to go into System information)
I reposted this in a busy Uk computer forum check there for replies
Good question.
By the way, I have a friend on Windows 98 who is struggling to do her job as a Fashion designer on a 600 mhz Pentium

God knows what resolution that is capable of? 800 x 800 ? I honestly don't think it can be worth improving
She's still on 56k Dial up and she'll be one of the last to upgrade to Broadband and Windows XP(albeit the slowest speed 512 mbs)