Contrary to popular belief, you can run games on Linux although there is generally a bit of hassle to get them running smoothly. Wine is a good start, it is a 'Windows Emulator' which basically means it allows you to run Windows programs on your Linux OS, there are special programs which configure the very advanced, technical and confusing settings for Wine depending on what game you want to run and provide a rating as to how playable the game is under Linux.
http://www.playonlinux.com/en/supported_apps-1-0.html
You've also got the paid product called CrossOver, which comes out of the box ready to play Windows games. There is a database on their website which tells you which games you can play, so if all of your favourites are on there, it might be worth considering to avoid the instability and hassle of Wine.
http://www.codeweavers.com/compatibility/browse/cat/?cat_id=2
As for Linux and viruses, as most people here have mentioned, Linux is not 'immune' to viruses and malware although the reality is Linux malware is much less common. Security upgrades and patches are released all the time which is more than can be said for Windows and Linux has a much more secure foundation. So long as you use common sense, be careful what you click on, ensure you set up a basic firewall (TinyWall for example), keep your software up to date (especially your browser, flash and java) you will be virus free
I notice a few people in this thread are probably unintentionally painting Linux as this rather scary, incredibly difficult to use, virus prone trouble box, when in actual fact, the 'beginner' (more user friendly) distros such as Ubuntu and Mint are actually in my opinion easier to use than Windows and much less frustrating.... Case and point, when something crashes on Windows and you click end task or kill the process, it still just sits there, laughing at you. When it crashes on Linux (those rare occasions), it just closes and you can get on with your life.
If you're not sure about whether or not to move to Linux then you can dual boot, run Windows and Linux on the same machine. This isn't actually as intensive as it sounds, since just one operating system is running at a time, your laptop would be under no more stress than normal, although due to the fact you have two operating systems you do lose some space on your hard-drive (external hard-drive for storing your documents is the answer here).
Now, I've been running Linux on my laptop (an old VAIO series one) without any problems for about three years and after switching to Linux, I would never go back. Honestly, it's not until you actually have to use Windows again after getting used to Linux that you realise how slow everything on Windows is, how long it takes to start up. How long it takes to open the start menu after you log in... Everything is sooooo long. Back to Linux and oh, well what do you know, I clicked on the menu and it just opened!