Weekly maintenance:
1) Ad-aware @ http://www.download.com/3000-2144-10045910.html

Check for up-dates, Then Check connect, if there's Then Check to install or click ok if nothing to install, Then Check finish, Then Check start, Then Check next, Then wait and fix what ever it finds, Then Check X to close window.

2) Spybot @ http://www.spybot.info/en/download/index.html

Download and install Spybot S&D, open the program, in the main program window, click on "Mode" in the upper tool bar. Then click on "Advance Mode". OK the resulting dialog box. New selections will appear at the bottom of the menu in the left column.
Click on "Settings". Click "Settings" again on the new menu that just appeared in the left column.
In the right pane, scroll down to the "Main Settings" group.
Uncheck the three lines that start with "Create Backups of------".

Scroll down to "Scan Priority" and check the box next to "Highest".

Scroll down again to "Web Update" and check boxes next to "Download Update-----" and "Display PGP Signatures Updates".

Don't mess with this:
(Optional: Select "Display available beta versions", if you don't mind getting an occasional bug that may require re-installing the program.)

Close the program, and run "check for problems"......Done!!

3) Download and install Ccleaner:
http://www.filehippo.com/download_ccleaner/

For a basic version of CCleaner with no Yahoo Toolbar, select the second or third install option as follows:
Even if you selected Option 2 or 3, if you do not want the Yahoo Toolbar installed:
Uncheck "Add CCleaner Yahoo! Toolbar", as it is checked by default during CCleaner Setup
1. Before first use, check under Options, Advanced, and UNCHECK "Only delete files in Windows Temp folder older than 48 hours".
2. A pop up box will appear advising this process will permanently delete files from your system.
3. Then select the items you wish to clean up.
In the Windows Tab:
Clean all entries in the "Internet Explorer". Deleting cookies will require re-entry of user names and passwords on next visit to sites that require users log in.
Clean all the entries in the "Windows Explorer" section.
Clean all entries in the "System" section.
Clean all entries in the "Advanced" section.
Clean any others that you choose.
In the Applications Tab:
Clean all (optionally, except cookies) in the Firefox/Mozilla section if you use it.
Clean all in the Opera section if you use it.
Clean Sun Java in the Internet Section.
Clean any others that you choose.

Then click the "Run Cleaner" button and it will scan and clean your system. Click exit.

4) Regclean: http://www.majorgeeks.com/download458.html fix all errors it finds and exit.

By now you should know to update before scanning.

5) Download and install Spywareblaster. http://www.javacoolsoftware.com/spywareblaster.html

6) Download and install Spywareguard. http://www.wilderssecurity.net/spywareguard.html

7) Disk defrag: http://www.auslogics.com/disk-defrag/

Then defrag and let it run till complete, Re-boot computer and you should be good to go.