Both of them suck, try Opera 11, it's the fastest current browser. You can have over 20 tabs, watch a movie, play music, skype, msn, pdfs, word and it won't eat up memory like Chrome or Firefox. It's also got a built-in torrent downloader. You can try running some tests yourself:
http://ie.microsoft.com/testdrive/Pe...k/Default.html - IE10 wins this one surprisingly, they can handle more graphics, chrome was last.