My computer is running really slow and I need advice?

[peacemaker]

First, backup all your data to an external medium.

Then, if you have no hardware problems, do this:

(1) Run a FULL anti-virus scan with a good virus scanner. Get free editions of Avast or Antivir. Use the latest virus definitions file. But don't install or run more than one anti-virus at the same time.
http://www.avast.com
http://www.avira.com

(2) Run anti-spyware scans with Super Anti-spyware and malwarebytes free editions.
http://malwarebytes.org/
http://www.superantispyware.com/

(3) Ensure all Microsoft security updates are applied.

(4) Run disk cleanup to delete old temp files and other junk

(5a) Run chkdsk once to scan for file system errors. http://support.microsoft.com/kb/315265

(5b) Run a thorough disk defrag. Use a good defragmenter for this, and also run a boot-time defrag to fix the MFT and page file if they are fragmented. Check out Diskeeper 2009, which is widely acknowledged to be the best defragger around. Their website has free 30-day trial versions. http://www.diskeeper.com

(6) Disable unnecessary background processes and services that take up memory.

(7) Make sure all the hardware components have the latest and most stable drivers. Video card performance in particular is strongly dependent on drivers.

You do not need to clean out the registry or mess with the registry in ANY way whatsoever. Deleting a wrong key from the registry can damage your operating system.

Good Luck!