Wow, Internet Explorer? How oldschool.

I upgraded from IE to Google Chrome a while ago, and the change in speed is amazing. I haven's used Firefox or Opera, but Google Chrome does have some customization capabilities. You can download themes from a select gallery, there are add-ons which you can download and will add little icons to your browser for easy access to them.

Whatever you choose is going to be a step up from Internet Explorer, but have a look at GenkiSudos post to see which will suit you best.