Just last week I had this issue. The computer had W98SE installed but when we hooked it to an LCD monitor to fix the problems we had another even bigger problem. It failed to boot! We had to get the CRT monitor out to do the work.

My suggestion is, if you have the monitor try it. However, it has been written often that an LCD monitor should only be used at it's native resolution. I would definitely not buy the monitor for that use.

Add a graphics card that supports it.
I think the graphics card and its memory is responsible for the max monitor size.

I have an old matrox card in a 98original that will do 2048x something, but it sure makes small things on the sony 17 inch monitor.

Thank you.

I'll look into a new graphics card, first. Any caveats to whether new cards will work with Win98?

I already bought the monitor (impulse purchase at $169 from microcenter), so if it's too big, I'll just swap it with 17" LCD on a 1 yr old Dell we have.

I paid around $200 for a dual head Matrox G450 32mb, Pci card ... now they're $25 plus some shipping on ebay.

If your new monitor had a Digital input, those cards new can be cheap. Just watch that it has the resolution you need.

I would be swapping the 21 inch over to my newer computer sudden like. You will love all that extra space I am sure.