|I have used PS2 adapters on USB keyboards before, generally on older computers that had no or limited USB usage (early Windows 95 machines) or USB problems and have not had problems. On the other hand, since Windows 98, I have not ever needed to load drivers (other than normal motherboard drivers) for using any wired keyboard for normal keyboard functions (special keys would probably need software to operate those options). I even recently purchased a keyboard with volume and mute buttons and they even worked without installing any software. Personally, I would use the USB connection (assuming you have enough USB connections) and keep the adapters in case you ever had problems and needed them in the future. The same goes for the mouse unless it has more than three buttons, you are unlikely to need software for them to operate. Note that for the keyboard and mouse to operate before Windows boots (BIOS, repair options, passwords, etc), they need to be plugged into USB jacks that are directly on the motherboard. USB jacks that are on hubs, expansion cards, and some front USB jacks (especially ones on combination card readers which have built in hubs) will not always work until Windows is fully running.|
I hope that this clears some things up for you.
You have to be a little bit crazy to keep you from going insane.