Hi Jason;
Actually, if your CSS is up to par and meets the W3C's CSS-1 specification you should have little problem with the same style sheet working in IE4+, Opera 5+, and Netscape 6+. The problem is usually because IE is so much more forgiving with HTML and CSS and can do a better job of guessing than Netscape.
Without seeing the CSS I can't really diagnose the problem - so please email it to me and I'll take a look.
If you're shooting for the rollover effect you don't need two different classes. For example: go with a.plain for the plain link, a.hover:plain for the mouseover that activates the color: attribute.
In either case, email me the CSS and I'll take a look.
Joel