You can download the original C&C for windows and there are instructions on how to get it to run on Windows XP.
Unfortunately the 'how to get it to run on XP' doc seems to be broken at the moment[1]. Using good old google cache you can view the doc as HTML though. Click here and then click on view as html:
(Click 'Continue Reading' below to see the install doc if you can't be bothered with the above)
[1] Amusingly the 404 error for the missing document itself has a 404 error since the server can't find the 404 error document it's supposed to serve.
INSTALLING AND RUNNING C&C GOLD ON WINDOWS XP
Follow the instructions below to install and play C&C GOLD
Preparing to Install
1. Insert either C&C disc into your CD drive
2. Open My Computer and explore the CD
3. Right click either the install.exe or setup.exe
4. select PROPERTIES
5. Select the COMPATIBILITY tab
6. Check the check box for “Run this program in compatibility mode forâ€Â
7. Select WINDOWS 95 from the drop down menu
8. Click APPLY then OK
9. Double click the .exe file you just modified to launch it
Installing the Game
1. When you’re prompted to update DirectX, uncheck the check box so you won’t install it. It is extremely important not to install this DirectX update
2. Follow the on-screen instructions to complete the installation
Note: Installing Westwood Chat is not required, it can be canceled if you desire
Installing the Patch
1. Visit ftp://ftp.westwood.com/pub/ccgold and download CCGOLDXPPATCH.ZIP
2. Unzip the files and copy thipx32.dll into the install directory of the game (default path is c:\WESTWOOD\C&C95). You may overwrite the old version of the .dll file
Preparing to Run the Game
1. Go to the install directory of the game (default path is c:\WESTWOOD\C&C95)
2. Right click C&C95.exe
3. Select PROPERTIES
4. Select the COMPATIBILITY tab
5. Check the check box for “Run this program in compatibility mode forâ€Â
6. Select Windows 95 from the drop down menu
7. Check the check box for “Disable visual themesâ€Â
8. Check the check box for “Turn off advanced text services for the programâ€Â
9. click APPLY then OK
Playing the Game
1. Select ÿStart > All Programs > Westwood > Command & Conquer 95 > Command & Conquer Windows 95 Edition. Or double click C&C95.exe located in the install directory (default path is c:\WESTWOOD\C&C95)
*Command & Conquer is not online compatible

I have 1 CD burnt NOD 95 and it is getting trouble when to install i’ve checked the check box and turn it onto Windows 95 Then i open it i get the preparing Installshield after that (100%) it says some nercercary files are missing cant instaal C&C GOLD plz help
The only thing I can suggest is that you make sure you’ve run windows update.
help! I have downloaded the installers for c&C gold..when I’m about to install it, I was prompted with “some necessary files are missing” window..please help! anyone of you have the necessary missing files? thanks!