Windows not recognizing USB harddrive

I bought a (cheap) USB 2.0 enclosure to use with my Macbook. I was planning to buy a 250GB 3.5" HDD to use with it, but decided to test it beforehand with a 40GB HDD I had laying around. The drive came from a desktop, and as such there were Windows and Linux ext3 partitions on it.
OS X recognized and mounted the drive fine, all of its partitions (couldn't mount the ext3 of course). After that, I installed Bootcamp and XP - the idea was that I could use just a minimal space for the Windows partition and install most programs in the external drive. Upon plugging the drive under XP, it came up as an unformatted drive, and offered to format it for me. I first thought it was some problem with bootcamp, but I tried it in my desktop and alas, XP would display the same.
So I wonder if someone has any hint of what might be going on. I never used USB HDDs before so I am not that familiar with its peculiarities. Can it be a master/slave jumper set up wrongly (even though I heard OSX has problems with that, not XP)? Are the Linux partitions the culprit? Perhaps the fact that it have LILO on it... Should I try fixing the MBR (and if so how?)?

And one more question... will the HDD head park when the enclosure is turned off? It makes a frightening noise...

 

There shouldn't be any issues with the slave/master configuration if the drive is in an external enclosure.

Can you see the drive from in My Computer? If not, then there's no partitions on it. They may not have been set up correctly.

Right-click My Computer from in Windows XP and hit Manage. Double-click Storage, then Disk Management (Local). Post a screenshot of that here if you could.

 

Do as Chaz advised.

On the right side of the screen under volume, select your hard drive. Right click and click on Mark Partition as active and assign a drive letter.

I just spent the past 2 hours trying to figure this out.

I feel your pain.

 

Thanks for the answers guys... I nailed the problem, but I can blame only myself. It turns out that the jumper was set wrong after all - but it was set on the "limit to 32GB" position... you remember, this was used with some older BIOS that wouldn't even boot with bigger then 32GB drives. So the 40 GB HDD drive was being reported as a 32GB HDD, and since I had partitions past that point, of course the partition table seemed all messed to Windows and Linux (OS X did an admirable job of recognizing what it could, even with some errors). Sadly I only figured that AFTER I had deleted all data in it.