You need to find proper driver for your sound card. I have couple of drivers, but it really vary from the system to the system.
Try first to search on Compaq/HP web site.
If you can't find it, I would suggest you to install Win98 on that computer (Win98 includes DOS 7.1, not same copy you installed, but it has all stuff needed to play those games).
Then use instruction on
this topic to set properly MS-DOS mode.
I have setup couple PCs this way, and all of them work without any problem with all DOS games I got.
If you don't have WIn98, or you are unwilling to install it, then you have to find specific drivers to your sound card, and install it in DOS in the order to use it. (but you can't use Everest in this case)
Hope this helps...