I've never really known one of these adapters not work with any machines I've used them on, but I suppose it could be possible. We can get these adapters in but they're not particularly cheap, about $35 once GST is added on etc and the only ones we can still get are a single USB plug with two cables coming off to connect both a Keyboard and Mouse (Obviously you don't have to use both but they're there if you need them).
I'd say reliability will come more down to how good your USB ports (i.e. dependant on your motherboard) are and how well your operating system handles USB, if it's a newer Operating System like Windows XP onwards or Linux from 2.5 Kernel upwards you shouldn't have a problem, if you're using something older like Windows 2000 though then yes I could envisage issues with recognising the USB converter properly. You can get a new USB Logitech keyboard these days for about $30 - $40 and mice aren't much more expensive either so it may be worth upgrading instead?
If you're anywhere near the north shore I'd recommend nipping into a little shop called "ACS" on link road, I bought a Logitech USB keyboard from there about a year ago (Before we started supplying PC stuff) for about $30 and am still using it now. Don't buy a DSE ownbrand one for the sake of another $10 - $15 getting a Logitech one, it'll last longer, feel and look better and be far more reliable.