137GB Drive size limit for external USB

Hi all - looking for a kind word to help me past my current dilema that has been baffling me for a whole week - I bought a Western Digital IDE 250 GB hard drive (just the hardware- not a retail version) and have it connected via a external enclosure (Bytecc ME 320U). This ext. drive is to be used for back-up purposes.

 

My problem is that I can't get the Dimension 8300 to recognize anything larger than 137 GB - I have tried all the issues i can. Can anyone suggest a fix??

 

So far I have tried:

1- Verify the Bytecc enclosure - they state the units are compatible for up to 300GB (although their documentation is vey sparse)

2. Tried WD Datalifeguard 11 to partion/format the drive - to no effect

3. Reviewed that the Winodws XP Home is 48 LBA enabled (the ATAPI system file is newer that what MS suggests is required so I assumed this was ok and I didn't revert to the file that they suggested would fix the OS side of the problem

4. BIOS - didn't get very far here - applied the Dell A07 BIOS flash, but with no effect. Tried to download a newer motherboard BIOS but can't determine who the manufacturer is for the motherboard (I tried the Intel 875P bios but that didn't execute) 

 

Any suggestions??