While translation keep me busy most of the time, and there's always underlying pressure to finish off a day's work, I have forced myself devote half about a day every week to check for updates to Windows programs, updates to applications installed on my system, running the Windows defragger to defragment the hard disk, and performing a data backup. Today, I'd like to share with you my once-a-week maintenance schedule with the main utilities I use.
1. Detect and update vulnerable programs
I use Secunia PSI (free for personal use) that checks my system, scans, detects and helps to update vulnerable programs. It provides links for easy download of patches and updates to keep your applications running smoothly. Here's a screenshot of the results of scan of the system by this application.

Try it. I found it to be very useful as it warns me of vulnerabilities.
2. Update checker
I also use the Update Checker from Filehippo.com that scans my system and produces a list of applications that need to be updated. Yes, this is also free, and shows updates to beta versions of applications too. The screenshot below shows some of the applications that I use for which updates are available today, and the download links.
3. Disk Cleanup
I usually go to Start/All Programs/Accessories/System Tools/Disk Cleanup (note that my menus are in Japanese so the above may not be the exact words used, but you should be able to find the Cleanup program) and cleanup my system of unnecessary files, such as temporary Internet files. That does free up several hundreds of megabytes of space and prepares the hard disk for defragmentation, which is the next step here.
4. Disk Defrag
I then go to the same menu as above and select Disk Defrag under System Tools (Start/All Programs/Accessories/System Tools/) to defrag my hard disk. The defrag process does take a bit of time depending on how fragmented your hard disk is, but regular defragging makes the process go quite fast and keeps my hard disk in good order.
5. Disk Backup
Finally, I back up my data using Acronis (to back up the entire disk) and also my own low level data backup method that I wrote about before.
To conclude, however busy you are, minimal maintenance such as described above will keep your system working like a well-oiled machine and save you problems in the long run.
Have a great day!