Vista Tutorial - TV Tuner V Freeview box?

TV Tuner V Free view box?

Hey, im looking for some help. I need some advice on whether to buy a TV tuner for my computer or not? Currently i am running Vista Business, which means that i don't have windows Media center? is this download able even though i don't have Vista Ultimate or Home premium?
Could anyone suggest any reasonable priced (< £40) TV tuners that have the basic channels with other UK channels.

if i was to buy a free view box and link that up with my PC, does that means i will have to buy an aerial for it to work?

And in your opinion which is better value and worth buying a free view box or TV tuner?

(Sorry, if im asking a dumb question i have little knowledge on this topic )

Thank You