The slowness issue is one we're always having to deal with. People complain that their computer is slow to start up. There are generally four types of slowdowns, and all have different solutions.
Slow to reach the login prompt.
The most common cause of this is that software is being installed. We generally release software and updates on Thursday. People are good about leaving their computers on, but sometimes a restart is required. You turn things off Friday, then when you restart on Monday, the software needs to be installed, so it takes several minutes to reach the prompt.
The best solution is to restart the computer when you go home instead of just logging off. It will install the software and be ready to go the next time you log in.
Slow to reach the desktop after logging in.
This is generally due to having a large profile. It wouldn't hurt to use something like CCleaner to clean up unnecessary files.
Slow before you can start working.
This is usually due to software starting up. If you have a lot, it can take some time before it's all ready. One option is to use Startup Delayer to manage your start up. Another is to uninstall any programs you don't need to run at startup. For instance, you can manually start AIM instead of doing it automatically on each startup. The less running at start up the better.
This may be a virus or spyware problem. It may be worthwhile to do a scan at Trend Micro's Housecall to see if there's anything causing trouble.
Another potential cause is lack of memory. Computers require more memory each year, and what was ample five years ago is barely enough to do anything today. If you notice your hard drive is constantly running, that's a good sign there's a memory problem. Buy new memory (or a new computer) and many of these problems will go away.