Who can tell me about trojan horse viruses?

I'm computer illiterate. I have to admit it. I am addicted to Scrabble. I don't buy stuff online, so I finally broke down and bought me a disc to download the game. I've been in Scrabble Heaven....up until this a.m. when I had a trojan horse alert and it said it was from Scrabble! aauuugh! Not my Scrabble!! I automatically sent it to the vault and removed the program from my computer. Will I ever be able to install my game ever again, or is it forever a threat to my computer?