Time Machine Questions

Ok, i just purchased a external HDD and i want to use it as my Time Machine backup HD.

I am going to plug it into my airport extreme so i can wirelessly back up the files i want to back up.

Now here is my question

Can i also use that same backup disk as a hard drive shared with both of my computers? A windows PC, and Macbook pro.

Like can i put files from my PC on it so i can access them on my macbook, without interrupting Time Machine some how? Will Time Machine delete these files that i put on?

I cant give you an exact answer on this but here is what im thinking

I had a External HD that I backed up all my stuff to on my old windows PC. When I got my MB I attached the External HD, the mac took the files (music, pics etc). In order to use it for time machine it needed to reformat the EHD.

Sooo Im not sure that youll be able to use the same drive for win and mac

I will admit that im no mac guru (im a total newbie) but im just drawing logic here

I keep several things on my TM back up drive including the TM backup from two Mac's.

Haven't used a Win machine in the house for about a year now, but that shouldn't be a problem either.

Thank you guys.

I plugged in the HDD to my airport extreme.

but how do i access the HDD on my windows computer??