I just found this the other day when I reinstalled Cubase on my recording laptop. The copy protection for Cubase LE is luckily (and thankfully) nonexistent if you have a working copy somewhere, although I did have to register a couple of DLLs with Windows. But after loading the software, even with the new Firewire interface, sound latency was awful--something like a full second round trip. It's impossible to monitor yourself through software when the delay is that bad, and although there's a direct mode on the interface, it involves opening up a mixer window and fiddling with the inputs. I didn't really want to do that, especially since I know that Ableton Live and Phrazor are perfectly capable of fast software monitoring with this hardware.
It turns out that Cubase LE can manage just fine, but the option is hidden. By default, Steinberg includes a driver that wraps the lowest levels of Windows functionality (MME, or maybe DirectX) in an ASIO layer. It works, but it's really slow. I'd known this all along, but I thought it was a restriction built into Cubase LE to encourage upgrades. That'll teach me to be cynical--they've just give the menu a very strange name. To change ASIO drivers in Cubase, choose "Device Setup" from the Devices menu, and then open the "VST Multitrack" tab. There's a pulldown menu that will initially read "ASIO Multimedia Driver"--when I opened it up, there was my Firewire Solo (as well as ASIO4All). Cubase still has trouble operating at the very lowest latency, but I had a comfortable experience running VST plugins on a recording track with 44.1KHz, 16-bit audio and a sample size of 128. Much better.
The only reasons that I can think for Steinberg's weird choices here are two-fold. First, they've obviously included the ASIO-MME driver for compatibility, and they don't want to take a chance on auto-selecting the wrong driver. Second, they've hidden the option in the "VST Multitracker" tab (which I had seen, but always ignored) because Cubase started as a sequencer instead of a recording workstation. Latency isn't as important for predetermined MIDI sequences, and from that perspective they might have referred to audio I/O as a "multitracker" instead of more straighforward terminology.