If you keep IE 7 and do not update/upgrade to IE 8 browsing should be noticably quicker. There has no fix as of yet, other than trying little tweaks here and there to resolve the issue with IE 8 and being slow. Steps for Both (IE and Firefox)
Another Tip - Remove any form of toolbar - Google toolbar, Yahoo toolbar, MSN toolbar, Windows Live toolbar.....etc
It is a common thing, especially when downloading and installing an application from the internet to be asked whether or not to have a toolbar installed. These particular toolbars is, another form of spyware that you are giving permission to have installled on your PC. And for those who didn't know this, and install not just one toolbar but two or more (I have witnesses someone having 5 toolbars) can be illustrated as such - if water represents the information sent back and forth across the internet, each toolbar can be looked at as a thin sponge that blocks the way of the water from getting to you. The simpler you keep your browser the faster it's going to be. I advise to go to the control panel - programs & features or add/remove programs - look for any application in the populated list with word "toolbar" in it and remove/uninstall it. IE and Firefox already have a standard toolbar built into it..no need for anymore.
Once all the toolbars have been removed from your PC - you should see an amazing difference. For IE 8, you could also try leaving your home page blank and/or configure IE so that you no longer use the tabs and have links open a new window. Try that see if a difference has been made.