PLEASE HELP ME WITH THIS DECISION!?

I want to get the game Call of Duty 4: Modern Warfare because my cousin has it and says it's awesome and I've seen some videos about it and I really want to play the game. But, I have a drawback on my decision. And that is: Do I get it for the PC or for my Xbox 360? You see, I want to be able to play multiplayer and I can't get Xbox live because my pc is at my grandma's house and I dont use my Xbox there. But I also like the Xbox controller better and it has the vibrations and it would probably run the game better then my PC will. There are two things I want to know and am begging for help with. Number one, which would be better, get it for my Xbox 360 or my PC (remember I can't use Xbox Live), do I go for multiplayer with the chance of alot of lagging, or do I go for single player without the lagging (Xbox)? NUMBER TWO. Is it possible to connect my Xbox controller to my PC and use it to play the game? I know this may be a stupid question but I have read some things about how to connect Xbox controllers to the PC and I was wondering if this would work for the game? Thanks!