If your computer is getting low on hard drive space on your system drive (C: drive) then that can adversely affect performance of your computer. There are a few things you can do to free up space on your hard drive.
The easiest thing to do is to do a cleanup of your computer to get rid of temporary files such as browser temp files and system log files. Rather than try and find these files yourself you can use a program such as the free CCleaner program that finds and removes all kinds of junk files from your system.
If you still need to free up space after your cleanup then you can delete or move some of your personal files. If you have too many pictures or MP3s for example you can delete ones you don’t care about anymore or move them to an external flash drive, hard drive or CD/DVD. Another option is to install a second hard drive in your computer and store your personal files on that drive to keep your main drive from getting full.
And another option is to remove any software you don’t use anymore or never used. Many computers come preinstalled with software that most people never use or never even know about. You can go to Programs and Features and uninstall these programs. Just be sure that you know what the program is before removing it.
If you end up installing a second drive you can uninstall programs from your C drive and reinstall them on your new drive. Just make sure moving the programs location does not affect the way the program functions. It should work fine in most cases.