Back in the day when computers had very little RAM, programs often had checkers to see how much was available before running, but the checkers often were only capable of measuring up to a certain amount.
The chances are that your machine has so much MORE ram than the developers were expecting, that it's simply failing to measure it properly.
In other words, the program thinks you don't have enough memory, when in fact you have more than it can even conceive of!
However, you could try this:
Right-click the program icon, and choose Properties
Click on the Compatibility tab
Check the box "Run this program in compatibility mode for" and select Windows 98/ME