Retroblast did a Light Gun Shootout awhile back, however that article doesn't seem to exist anymore.
I can't remember how accurate they said this one was, but I do seem to recall them saying it only works with Windows95 (so 98 should be fine too).
I have seen some interesting looking guns on these Chinese sites, even one that looks a lot like ActLabs older VGA gun that they were selling for around $20 (but discontinued that one and now you can only get the one that costs around $100). Doing the whole bank transfer thing for payment always made me shy away from buying one. I just didn't like the hassle and extra fees, plus there could be import taxes on items like these too, but I can't say for sure on that.
These pop up on eBay now and then too. It would be interesting to see if they will work with XP and how accurate they really are.