If you downloaded your copy of Trainz, then the links are still available to you on your Planet Auran page. This under your purchase history, and it lists the links plus the serial number for the program.
Antimalware programs are worth more than you pay for them in the long run. For as little as $30.00 a year, you can protect up to three computers using Trend Micro's Internet Security 2010.
In all of my years of computing, I have always protected my computers, and only had one virus. A combination of a good antivirus package plus cogniscent computing practices prevents malware infections.
Hope this helps!
John
