Free RAM by selecting startup programs and services

[Overnight]

Go to folder "c:\documents and settings\user_profile\start menu\programs\startup".
Delete shortcuts corresponding to the programs you think useless.
For common programs, choose "All Users" user_profile.

To deactivate programs or services launched from registry entries, launch this one : "c:\windows\system32\dllcache\msconfig.exe".
Click on "Startup" tab and uncheck the programs you think useless.
Click on "Services" tab and uncheck the services you think useless.
However, be careful because deactivating some services could lead to system crash.
You may use Process Explorer available in Downloads to identify essential services.

Nevertheless, when programs or services are deactivated with msconfig.exe, they still appear in the registry and could be reactivated
without your knowing because of new installations or system recoveries. Thus you can delete them directly from the registry.
Launch this program : "c:\windows\regedit.exe".
In the treeview on the left, find the following entries :
"HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion" and "HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion".
Thereafter, delete "ab" string values in the right pane in "...Run", "...RunOnce", "...RunOnceEx", "...RunServices" and "...RunServicesOnce" subkeys.