honestly though, i have actually had reason to need 64bit:
i am someone who tends to keep many tabs open, like...a lot of tabs...i have actually gotten opera's memory usage to around 3gb (though it is usually between 1 and 2 gb)

the current instance i am running probably would be using more than that if i hadnt started putting my laptop in airplane mode before launcing my browsers so that i can keep all my tabs at ready without needing to spend a few mins loading the tabs at startup (and to conserve memory - an unloaded webpage doesnt use nearly as much ram).

(jeeze what will happen when it starts using webkit)

but really
firefox - meh, never had any real appeal: it has extensive extension support, but unlike opera it lacks a solid core feature set (which is fine for some people, but i just dont get it)

chrome(ium) - such a memory hog, it was because of this that i realized that i came up with that starting in airplane mode trick

IE - its ie, jeeze it crashes left and right, can barely remain stable with more than 10 tabs, and webpage development is mostly "how do we make this page? ok now how do we force ie to render it?"

safari - its pretty much like ie, but from apple, it is just as unstable and has less opportunity for customization (cannot tell it to ask me where downloads should go...they always go to the downloads folder...why apple why...)

opera is pretty much the only good browser out there, especially for people who push their browsers
but you know what they say about operas and large women
and webkit sure is bloated