TF2......quistion?

i have a 360 version of tf2 (team fortress 2) but i heard that computer one is much better so i have severel quistions.1:what do i need to enhance my computer to playthis game cause i had zoo tycoon and it lagged so i can only wonder what will happen with an online game.2:How much will the enhancement cause for example i need to get a graphics card and that cost $........3:Is it worth getting the same game with more maps rather than 5 on 360.4:can i play with my 360 controller and mic(has usb controller).and5:how can i get my computer to go faster cause it is soooooo slow..... o yea and i did nothing to my computer beside add a wireless thing to it to connect to my wireless rouder my computer is by sony verrrry slow.if you have an 360 acount my gt is Sophist526