I use FF on my main gaming pc (using it now, actually), and Chrome for my laptop. Chrome seems to be a bit zippier on the lappy, but that is entirely subjective since I loaded FF with so many add-ons on my computer that it isn't even funny anymore (do I really need a weather, time, and TV schedule app?) Also, Chrome seems to have a really nice minimalistic and small UI that's looks uber-pretty on my small-ish laptop screen, while I could spare the real estate on my PC (though I HATE multiple toolbars: see comment on add-ons above). Also, Chrome is one of those browsers that has a better implementation of HTML 5 (from what I've been told), so it may be worth a try.
In short, if you can't roll FF, then in my opinion Chrome will be the best bet. Nothing wrong with Opera, but they make better mobile browsers imho. IE8 are for MS employees, grandma's, child-eaters, cthulhu-worshipers, animal-sodomites, and banking executive.