Removing unused programs does not increase performance (unless it's something that runs at startup). Since your Internet is very slow, it sounds like you may have malware so you will need to run some scans. Follow these steps:
1) Clean up the disk. Uninstall unneeded programs (especially those that run at startup and/or put something in the system tray), run Disk Cleanup, and defragment the drive. This is a good first step that will almost always take a few seconds off boot time and application loads for any computer.
2) Stomp auto-starting programs. Click Start > Run and type "msconfig" at the prompt. Click the Startup tab and look at all that junk that loads when you launch your PC. Do you really need "Adobe Reader Speed Launch"? Probably not. Turn off anything else that looks useless, but be careful not to disable your anti-virus and important system components.
3) Run a full anti-virus and anti-spyware scan. I would recommend AVG Free anti-virus, Malwarebytes and SUPERAntiSpyware remover. These programs are all free.
4) Clean up the registry. CCleaner, available at http://www.ccleaner.com is free and worth running. It will also remove unused files from your system - allowing Windows to run faster and freeing up valuable hard disk space.
I strongly recommend using Firefox as your primary Web browser, It is safer and better than Internet Explorer. Get the add-on NoScript for Firefox to prevent click-jacking. The AdBlock Plus extension will allow you to surf virtually ad-free. If you add-on McAfee SiteAdvisor, it will warn you of potentially harmful sites. I also recommend CCleaner which is a free system optimization and privacy tool.