PS/2 to USB adapter suitable for gaming?

I've got a couple of great ergonomic keyboards that I don't want to replace, but I'd find it useful if I could connect them to a USB hub (for a variety of reasons). And gaming is important.

I tried a "y-mouse" adapter, and while it did indeed press keys when I pressed keys, it wound up being totally unsuitable for gaming; it wouldn't "hold keys down" as long as I was doing (in other words, if I pushed W to go forward, eventually my character would stop as if the key had been lifted even though I was still holding it down).

So now I'm gunshy about USB keyboard adapters. But I'm sure there must be one out there somewhere that's good enough for gaming. Any suggestions?

-->VPutz