K-Meleon

• Simply a great little browser. Gecko-based, like FireFox is; if it were a motorcycle, it would be the same engine in a lighter frame. Which would probably equal more fun. And it does. Doesn't have the features that FF has when viewed out of the box, but on the other hand, it's much more customizable.

Miranda IM

• Oh, how I love this multi-protocol messenger. It's small, it works with a shitload of protocols, and it can be configured to do almost anything you want. Works with user-created plugins. And it can be made to look like whatever you want it to.

Irfanview

• So much more than just an image viewer. This is usually one of the first programs I put on a computer if I'm setting it up for a friend. Yes, it is a great viewer, but it's also got quite powerful image editing features. Great for cropping and resizing pictures, batch renaming, and much more. Don't leave home without it.

One small caveat: make sure that you don't let it install the Google browser plugin. Unless you want that, of course.

7-zip

• Everybody needs an unzip utility. And this one works fine. It deals with many different formats and it simply does the job. Worth a try!

FileZilla

• The best FTP-client I've seen, and I've seen plenty. FileZilla has all the features I could ever want and is very stable and not too complicated.

I'm sure I'll think of more tomorrow, and I'll be adding them to this list.

*zzzzzzzzzzzzzzzzzz*

Tommorrow's here, and yes! There's more. How could I forget the three things any computer needs for security: virus protection, a firewall and something to weed out adware.

AVG

• Great free anti-virus software from Grisoft. It performs as well as lots of paid software, in fact even better than some of the stuff that people pay for. It doesn't use too much of your computer's resources and I've been using it for years without any problems. Its internal database is updated every day.

Kerio

• Kerio is the old name for a free personal firewall that's now made by Sunbelt. I have used it for years and liked it a lot. You get the 'free 30-day trial version' and after that, unless you buy the program (currently it's 10 dollars so that's not very steep) it gets downgraded to less features. I've always been happy with the free version of Kerio so I reckon it's still a decent product. (The reason I'm not using it anymore is that I'm now behind a hardware firewall and don't need it anymore.)
• Another good option would be ZoneAlarm, but I'd prefer an older version, namely 2.6, which is still available from Oldversion.com. Because newer isn't always better!

Finally (for now), two great tools that help you get rid of spyware and adware:

• AdAware
  

• SpyBot Search & Destroy.

These two are not meant to be running in the background, rather, they're programs you run every now and then, to scan your system. Highly recommended. I'd get both of them since one will find things that the other won't.