I do a number of things on any computer with a Windows installation.
1. I partition my hard drive into three sections. The first is my primary partition, where the Windows install and most programs are located. The second is my data partition, where I place any data and some programs. The third is a large files partition, where I put things like virtual hard drives, disk images, and other large files.
2. I use
CCleaner to wipe all sorts of files that I don't use and to get rid of some registry clutter.
3. I use
Defraggler to defragment my files, and then defragment my freespace to move all of the files together.
4. I run my internet browser (
Firefox) and IRC client in
Sandboxie, which prevents them from doing anything malicious without me seeing it first.
5. I disable any services that I don't use and move any startup programs that I don't need to a folder where I can launch them if necessary.
6. I use FileHippo's
Update Checker to check for updates to any programs I have installed.
7. I probably should have mentioned this first, since it's actually the first thing I do, but this isn't in chronological order anyway. I set the swap file (also known as virtual memory) to a fixed size, usually about 1 or 2 GB more than my current RAM, and I run
PageDefrag to make sure it's not fragmented. The reason I do this first is because if it's fragmented on a relatively full disk, it can be tough to defragment.
With my Linux installations, I don't need to worry about a lot of this due to the way I set them up. I partition them during the install, so I don't have to concern myself with shrinking partitions or anything. This includes a swap partition which houses the swap file, so it won't fragment to begin with. The built-in package manager usually deals with updates itself, so I don't need to install a separate program for that. And since I'm not installing anything I don't plan to specifically use, I don't need to go through and stop certain programs from running.