There are a lot of people still using Windows XP out there. Here are a couple of ideas for tweaking performance of your system.
The first one might seem a bit counter-intuitive but yes, fixing something in Internet Explorer can help with your whole system. First step, I cannot recommend enough that if you are using IE and haven't upgraded to version 8, please do so. Lots of web sites don't play nice with IE6 now and IE8 offers noticeably better performance than 7 does. Then open your browser and you'll see a menu item on the upper right toolbar that says Tools. Clicking on that gives you a drop down menu that has as its last choice Options. The dialog box that opens when you click on that has a section with the title of Browsing History that includes a Delete button. Clicking on that button brings up another box with multiple choices that you choose with check boxes. Looking at the choices under the horizontal line you'll see Temporary Internet Files, Cookies, History, Form Data, Passwords and InPrivate Filtering Data. Above that horizontal line I mentioned earlier is an option to keep all of that data for any web sites in your favorites list. Personally I just worry about the Temporary Internet Files option since that accounts for the really big data items such as every single graphic on the web sites you browse to. I just choose that one item and click on the Delete button. But if you're worried about privacy or want to wring every last bit of space out of the process you can go ahead and delete them all. Just remember that getting rid of the cookies and passwords can cost you some convenience on web sites you use so much that you don't want to log in every time you go back.
Another tweak is to get rid of some of the graphic bells and whistles used by Windows for all of their menus and dialog boxes by default. Find your My Computer icon, whether you have it on your desktop or in your Start menu. BTW, if you use it a lot it's convenient to have it on the desktop and you can have it there just by right clicking on it in the Start menu and choosing Show on Desktop from the menu that appears. Another option that appears is Properties. If you right click on the Properties selection a dialog box pops up with multiple tabs. Click on the Advanced tab. Click on the Settings button in the Performance section. What I do is click on the radio button for Adjust for Best Performance, which clears all of the radio buttons and then adjust the details by scrolling down and checking these options: smooth edges of screen fonts, use common tasks in folders, use drop shadows for icon labels on the desktop and use visual styles on windows and buttons. This gets rid of lots of "special effects" while not changing the appearance very much at all. And it does improve performance noticeably, though not by a huge amount. Things are just snappier when using menus and when Windows many windows pop up.