Yeah, as long as the external hard drive is connected over USB 2.0 / Firewire, then you're fine. I'm not positive that USB 1.1 can get around this barrier, but USB & Firewire are both Serial interfaces that don't share the same problems of Parallel ATA devices (hence, the 137GB barrier of 28-bit).
Now, there are other options for you. You don't have to invest in a more expensive external hard drive. Instead, you can buy an add-on PCI IDE controller card that uses 48-bit addressing. Unlike the standard 28-bit addressing your motherboard is limited to, the PCI card has an upper limit of 144 Petabytes - that's almost 151 million Gigabytes!!
Promise I hear is a reputable company to deal with. Be weary of buying a generic card; you might get stuck with generic support!!!! ~cdogg
"The secret to creativity is knowing how to hide your sources."
- A. Einstein