I owned a 1010LT. No, I didn't use it under Windows, but their Mac drivers broke nearly every time Apple released a software update (about every two months). Every little thing broke their drivers. It was the worst experience I've ever had with any device driver. Ever. I could probably rant for hours about all the things they did wrong in developing the driver... like using a startup item because they didn't want to bother doing proper driver matching/enclosure for 10.2 support. Instead of doing something that would take fifteen minutes, they did a ten minute hack job. If that sort of hack job is what the XP drivers look like under the hood, I wouldn't expect Vista drivers any time soon....
I've also seen dozens of people saying how buggy their XP drivers were when they first released them, but that was so long ago that most of those driver engineers probably don't work there anymore. Their Mac drivers have had to deal with changing OS versions more recently, and thus are probably a better indicator of things to come for Vista.
I finally sold the 1010LT when Apple dropped PCI two years ago and bought a FIREPOD. It was also problematic, but at least the drivers didn't break. I finally had my first solid recording setup when I moved to an all-MOTU studio, and I haven't looked back. Now, everything just works.
And then, there were the hardware bugs. Despite being a 3.3v card, the 1010LT was incorrectly notched as 5v-only, making it incompatible with PCI-X slots in the early PowerMac G5s. They charged a pretty good chunk of change to "upgrade it". As best I can tell, it involved using a Dremel to cut a new notch in the board. The problem is that the redundant ground they removed was apparently important for grounding the power filtering caps that powered the output path. The output signal constantly chirped with CPU/GPU noise after the upgrade.
No, I wouldn't recommend any M-Audio interface to my worst enemy after my experience. I could go on and rip on them for another page about the M-Audio FW1814, but it suffices to say that my experience with the Delta series was very, very different from yours.