It's fairly easy but requires a few different pieces of hardware. For the I/O the easiest to obtain/cheapest is a j-pac from ultimarc that converts the jamma output to USB.
https://www.ultimarc.com/control-interfaces/j-pac-en/j-pac-jamma-interface/
If you want the cabinet lights to work you can get a LIT board to handle the lighting. (You also need to bridge a few pins on the pad I/O connections to get the pads working, a LIT board will do this for you but otherwise it's just a paperclip or something else to bridge two pins)
https://dinsfire.com/projects/lit-board/
If you still have the CRT monitor in your machine you will need a way to output a signal it can display. There are some video cards out there that can do a 15khz RGB signal, or you can try the CRT emudriver which are drivers that allow some older ATI video cards to output 15khz.
The other option that most people go with is to replace the CRT with an LCD monitor, then you'll have no worries about signal but you won't be able to run the original 573 without some sort of signal converter.
Once you get that all set up then you have lots of options for software. You can run stepmania which is an open source DDR engine. You can load it up with all of the official songs and there are thousands of custom made song packs for it. The DDR clone "In The Groove" was made on a branch of Stepmania and it has a lot of benefits over the official software such as >60 FPS support and the ability to customize just about everything about it.
There's also a version of Stepmania called Beware's Extreme which is a very faithful clone of the DDR Extreme UI. You can then load it with a bunch of newer/custom songs.
Finally there is cracked data. This is the official software that's run on DDR cabinets. You can get data for any version all the way up to the newest which is called A3. There is also an omnimix out there that runs on the A20+ software and has literally every official song ever made for DDR included in it. There are even several private servers out there so you can access all of the online features and save your user profile/scores like you would in the arcade. There's also programs that emulate the eamuse servers so you can emulate a server locally.
It sounds like a lot but it's not hard. The worst part will be getting a nice looking image on the CRT if you still have that in your cabinet.
You also don't need a very powerful PC to run most of these options. I used to run mine on a dell optiplex 780.