Mozilla and Netscape are basically the same program,
except AOL owns Netscape so don't use it!
Firebird is just Mozilla without an HTML editing program, and without an email client.
Opera is good to, you have alot of options with opera, page sizing for one. There is a box at the top right of the opera screen with a drop down list of percentages you can make your screen 50%, 40%, 30% etc smaller or larger
But its kinda tricky getting plugins to work on opera: Quick time, Java etc
So get Mozilla and never look back, one other cool thing. Mozilla is totally opensource so you an download betas and alphas all the time, some of them have new features, and some just run better, its cool.
AND DUMP XP!! Get SuSELinux, or any variant of Linux, Ill still be happy........Wait no Lindows!