Time Machine problem

Hello, first post here. I have searched extensively but can't find an answer to my problem...

I have a new macbook, OS Leopard. I am new to Macs, but am learning. I took my old usb hard disk, with lots of files on it and allowed time machine to make a back up on it of my mac. Since then I can no longer find my old files, and the hard disk is not seen on my windows PC... When I allowed Time Machine to perform the back up I admit I wasn't paying too much attention, but I don't think I allowed the mac to format the hard disc....

Is there any way to find these files, or any way to browse the disk other than with the finder tab. And can I no longer use this disc at all with my windows machine?

I would be really grateful for any help. As I said, I did search. There were some really important files on the disc that I would hate to lose...

Many thanks

Right click on your USB drive (on your desktop) and select More Info. In the General section it should indicate the Format of your drive. What does that say? If Mac OS Extended (Journaled) the drive was likely repartitioned and any files you had on it would be gone.

Yep sounds like it formatted to me. I have my external drive partitioned. One for Windows files and one for the Time Machine back up.

@dalison. Yes, that is there when I right click. But where it says capacity there is missing about 20 gigs, which is about what I had on there. It was a 500 gig hard drive, of which around 490 was useable. Now it was capacity is 460 gigs. So I am still hopeful my stuff is still there...? So, is there any way that my windows PC can see this disk and browse through what is there...

A million thanks for the replies, and so quick! Am really grateful to you all!

Cheers

Have you plugged the drive into your Windows PC? Windows are usually formatted NTFS

Try plugging your USB drive into your Windows machine. If it is not visible this may help walk you through finding the partition:

http://support.microsoft.com/kb/309000