Startup items:

Here is a HUGE culprit of slowing down the average PC, especially at boot times.
See all those icons in the lower right corner of your screen? (System Tray), Those are all being loaded on startup, and those are not all of them either! If your wondering why you have to wait a minute to use your computer after startup, it is because all of those items are loading after Windows has started. They also use up memory just sitting there. Removal takes a bit more knowledge, or research, then the previous two steps, but you can do it!

First off, if you know what these items in the tray are and do not need them running, you can either right click an icon and look for options or a "run with Windows" option. Otherwise, you can double click any icon to open the program and look for options from there. Some are easy and common. Quicktime, AOL and RealPlayer are good examples of items that do not need to be there.(Most apps, by default, are configured to run on start up but they can easily be stopped in most of the options settings under 'tools')

CCleaner also has a startup manager (what a sensational little program this is).
Click tools, then startup. You can delete any unneeded items from there. Be careful, there is no backup, so either look up the program on Google or ask on this forum if you want to know what an item is for. Because the startup loads drivers and some programs you may need, be careful removing items you are unsure of.