There are N64 to USB converters around as there are for just about any other console controller
The only things you tend to need extra drivers for (USB controllers/converters) is stuff like rumble that no controller can have on a PC without a driver, this includes PC controllers
The first PSX to USB converter I had also had support for N64 aswell as PSX, (not at the same time it was PSX or N64)
Wired 360 Controllers are also Windows Controllers anyway, but also need a driver for rumble features, but everything else will automaticly work with no external drivers
Basicly all the above will just use the default HID Device drivers that is part of windows, infact most USB controllers do, aka most almost all (Not every single one does, just the majority) are plug and play, just features like rumble are not plug and play [still best to install any external drivers though if they are provided as they will be specialised for that controller and may add extra features, like setting buttons to keyboard presses, Macro commands ect or rumble features that I have mentioned too many times]
[Olde skool comps aka win98 to 2K machines I remember seeing a home made serial converter for N64 and PSX controllers, personly I actually made the PSX one it even supported my multitap and memcards slots, if you also added power to it (I did) it adds rumble support also, if you are lucky there may even be a USB version around that you could make yourself]
Note: wireless console controllers do need drivers as they tend not to run from USB but only charge via USB
Personly I feel an actual console controller will always feel best, specially one you are used to the feel of, never did get the feel for the N64 pad personly, but I not saying just because I couldn't get used to it you shouldn't (that would just be silly) I do enjoy N64 games via a GameCube controller though via my Wii
There is one PSX to USB converter I will warn anyone about and thats a one that looks like a miniture Xbox and can be connected to Xbox, GameCube/Wii or USB although works great on the Wii/GameCube/Xbox, the USB support does not work with Windows 7 or Vista, admittedly not tested this with XP or lower though
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