Actually, as long as the game(s) in question aren't messed up by faster computers, I've had quite a bit of luck with the following conditions.
I've never been able to get any PCI sound card to work well in DOS. Forget using a Creative Labs PCI card completely. DOS support from Creative after ISA is a major joke. I've tried a couple of others (don't remember the exact cards,) and had similar problems. They either eat up too much conventional ram, or they just don't work right. One driver even caused my computer to hard-lock when I used a <shift>+letter command (typing a capital letter, using the <shift> key to walk fast or slow, etc...) So, you would really need an ISA slot or 2 and put an older sound card in.
As for graphics, most PCI cards can handle any DOS based graphics demand without any problem. What you have to be aware of are any games that are hardware 3D capable. For these, you just have to have the correct card for whatever option(s) those games offer. Usually an 8 or 12 meg 3d card is enough for most DOS based games.
Finally, the mouse. If you have a motherboard with an ISA slot, then most likely you will have a PS/2 port for the mouse (and usually KB as well.) A USB-PS/2 adaptor is usually fairly easy to come across for the mouse. Don't know if they work for USB keyboards, never had one of those. If push comes to shove, go find an old COM port mouse (they are still out there,) and use a free downloadable mouse driver (like cute mouse.) Also, the DOS 6.22 extras disk has a mouse driver that works with either a COM or PS/2 mouse, but it is a memory hog.
The last issue would be the joystick. I know of no DOS drivers for USB joysticks. But, with an old ISA sound card, you have a game port you can use. Now, here is the real problem. The older sound card game ports had problems with faster machines. To fix this (prior to USB joysticks,) I had to buy a game port dedicated card with a speed control box. This would allow me to adjust the timing on the game ports (there were 2 on the card I used to have,) so that your game port joystick wouldn't have problems on the faster machine. I haven't looked into the availability of these recently, so you may have to look somewhere like eBay for that (if you end up needing it, not all sound cards had a problem.)
Adjusting for all the above, I've managed to get pure DOS working just great for DOS games on up to a P3 system. Haven't tried it with a P4 or later, though. Mainly because I haven't found a P4+ that also had one or more ISA ports. Well, actually, I did find one, but I wasn't really willing to pay $500 for it.
