Slow computer - too many programs?

Would the amount of installed programs on a computer affect it's speed? As in, the more programs that are installed, the slower the computer becomes?

The computer I'm asking about is not mine, it's a relatives. It's a Core 2 Duo (E6300), 4 GB RAM, 200 GB HD, Win XP. It has a total of 378 programs installed. Of those programs, 280 are games that don't require a CD/DVD. They were bought and downloaded from websites like Yahoo and BigFishGames.

The computer was reformatted during the summer of 2007. I've been noticing performance problems (slowness) over a period of six months or so. I can confirm with 100% certainty that there is currently no malware of any kind on that computer. By slowness, I mean that it takes longer than it should to open a folder or program. The boot time is also slow too. The amount of startup items is the same as before the slowness started. My laptop that has 256 MB RAM, 2.6 GHz Celeron, and Win XP boots faster and is faster!

I can't believe that all those programs would be causing the slowness, but I thought I'd ask about it anyway.

 

Welcome to Major Geeks.
If you are positive that there is no malware, take a look at the Startup list. Try to trim it down.
Also a good defrag can do wonders.

 

All the programs installed will not slow down the PC unless they are in startup menu or are running.
One way to help speedup is to clean out all the junk files and clean the registry.

http://www.majorgeeks.com/CCleaner_Slim_d4191.html

download and let it clean all that it finds (it's perfectly safe) and then in reg mode let it clean that.
It also has an application to alter the startup menu, un-click the programs you do not need on startup then reboot and see if it has improved.

 

What antivirus? If the av is set to scan everything that is clicked on, that could slow things opening.
Are there lots of desktop icons? That will slow things down. I usually try to clear off some of the icons by moving them into folders on the desktop.