[RGamer2009]

I have a VERY old version of Sonic CD for the PC.

How old? Windows XP doesn't run it.

Says it needs "DCI-Compliant" drivers to run.

What does that mean? Is there any hope of getting this to work on a Modern PC?

[Scleros]

Says it needs "DCI-Compliant" drivers to run. What does that mean?

DCI in that context probably stands for Display Control Interface which was a Microsoft/Intel video standard precursor to DirectX and the Direct Draw Interface (DDI).

Is there any hope of getting this to work on a Modern PC?

There's always hope... with enough effort... custom coding... reverse engineering... etc.

I usually find it easier in XP to fiddle with the game's shortcut's compatibility mode settings first, and if any of those don't work find some old hardware of the same vintage as the game and setup a machine just for the game. Even if it is possible to get the game to load with the compatibility settings, often implicit assumptions were made about the underlying hardware that are no longer valid and the game may do funky things like run so extremely fast that is it unplayable.

Another option is to look for a modern version of the game. Many classics are being revised and re-released.

[shazamataz]

I have a lot of games that I absolutely love that are now useless on my new computer.

I managed to find some of them online very cheap.
Just do a Google search for the game you are after and see if you can find it available for download. The official SEGA site may even have it.

I used to play the game Theme Hospital a lot years ago and I couldn't find a version online that would work on my computer, I was gutted... then I was browsing through the online store on my PS3 and found it! Only $8 I believe, bargain.