External hard drive inaccessable

[Mayhem]

When I turn on my Lacie external hard drive (160GB, USB2) Windows Vista Home Premium tells me I can't use the drive until I format it. I've been using the drive for years and it has over 120GB of data on it. Needless to say, I don't want to lose this data. Can anyone recommend me a good (and preferably free) recovery program so I can still recover the files from that hard drive?

Thank you.

[Aegis]

What's the file format of the external drive?  NTFS?  FAT32?

[Mayhem]

It was FAT32 but I converted it to NTFS about half a year ago. It has always worked without problems up til now. Sorry, I forgot to mention that.

[patio]

How is it being reported in Disk Management ? ?
Right clik My Computer and select manage...then disk management.
You may want to re-boot first.

[Mayhem]

I can't tell right now, it's busy analysing the drive so I can't access it now.
Rebooting didn't help, that was one of the first things I tried. I'm fairly positive the MFT is messed up, so I'm looking for a reliable program to recover my data from the drive.

[Mayhem]

I'm trying Disk Recovery Wizard, something I found here, but it's been scanning my drive for over 27 hours now and has barely reached 2% of the progress bar. Is it supposed to take this long on external hard drives (USB2) or is this program useless? The drive has a lot of activity going on, so I assume the program is doing something. But at this rate, finding the files on the drive will take weeks and recovering them might take even longer!
On top of that, I'm not even sure if this program is any good. I don't know if it'll be able to recover my data...

So who can suggest a good data recovery program, in case this one turns out to be a waste of time?