Windows 95/98 have very good support for playing DOS games. I have a Pentium II 400MHz with Win98 and and am able to play Duke 3D, Descent, Zoop, Wacky Wheels, Raptor etc within a DOS Window (full screen of course). Make sure your sound card supports DOS emulation. Open a DOS window and type SET and press enter. You should see all your DOS environment variables, among them should be a line similar to this:
BLASTER=A220 I5 D1 H7 P330 T6
Your values may be different but the BLASTER line should be there nonetheless to offer Soundblaster compatible sound.
Win95/98 also have a plain DOS 7 option built-in. Before Windows boots up hold down F8 and you will have menu of options, COMMAND PROMPT ONLY bypasses loading Windows and will give you a plain DOS prompt. The caveat is there is no CD-ROM or other drivers are so you will have to manually add them to CONFIG.SYS and AUTOEXEC.BAT