PC pads are shit period, the whole concept of a pad for a pad for a pc is a silly one, but if its absolutely essential you need to devolve the input device, then you certainly don't want to buy a pc one.
A smarter option is buying a console pad and a converter. Think about how much money Sony and Nintendo have spent on developing their pads over the years. These are the soul input devices for their consoles and as such are technically superior to anything you'll get on the pc that has been chissled together by a couple of monkeys.
So invest in an input device. and use a console pad. I use:
http://www.lik-sang.com/info.php?catego ... s_id=2143&
Which is okay if a bit ropey (but its cheap) and can use a Gamecube pad (not the wavebird though

), which is far better than any pad available for the PC natively.
Then grab a program called JoytoKey and map your pad as mouse/keys instead of direct input (microsoft = shit). This way it will work flawlessly in any game, albeit inferior to keyboard and mouse 90% of the time. The added bonus is that you can use it to control your pc if your a lazy sod
This one supports dreamcast, PS1/2 and Gamecube console controllers:
http://www.lik-sang.com/info.php?catego ... s_id=4532&
On a personal note, at the end of the day your crazey if you want to use a pad for the pc beyond racing/flight sims games imo, your sacraficing one of the key reasons pc games are technically superior in the vast majority of genres (and the only ones really worth bothering with beyond the exceptional adventure game of course).
I never use the gcn pad, I mean I've had a couple of gos in GTA:VC with it, but if you want to play seriously, its not worth bothering with. I used it more as a 'remote control' since the wire extends for ages.
If its the keyboard layout that's daunting, this thing is a must:
http://forum.dead-donkey.com/viewtopic.php?t=6746
Bold = advice to read first and try with your current pad.
edit: oh and emulators, those are good for pads. Nothing else though, not any genre that PC excels at
