You shouldn't need to download anything since those games should work fine in XP. (Assuming you like XP's sound emulation and that your not encountering the 16bit subsystem problem.....or the giveio.sys problem or inability to use EMS problem or...etc)

What exactly is your problem with running the game? Have you tried to run it?

I get this message when i try to run Duke 3d

16 bit subsystem

C:\windows\system32\autoexec.nt. the system file is not suitable for running ms dos and windows applications.

I get this when trying to run other old games like warcraft1 as well as the others i mentioned.

Read this: 16-bit subsystem error "Your system is not suitable for running 16-bit apps"