Copy these files to your GTA1 folder:
Run GTAWIN/gtafree.exe
These files were extracted from the free version of GTA, so you don't have to d/l the 328MB file if you already have the GTA CD.
There won't be any music unless you make a GTA\Music directory and put track1.wav to track10.wav in there. You could rip them from your GTA cd or any audio cd :)
Here's the file listing if you were curious:
12,083,444 Track1.wav
6,350,444 Track10.wav
39,249,044 Track2.wav
51,244,244 Track3.wav
50,891,444 Track4.wav
39,778,244 Track5.wav
58,123,844 Track6.wav
16,846,244 Track7.wav
46,305,044 Track8.wav
5,380,244 Track9.wav
326,252,240 bytes
GTAWIN\gtafree.exe was actually called Grand Theft Auto.exe and in GTA\WINO directory but I renamed it so it wouldn't overwrite the old exe.
F_RSTAR white.RAW doesn't appear to be used but I included it anyway since it's small. You can easily view it by renaming it and overwriting F_RSTAR.RAW, then it will display on the title screen.
gtamp.com
gta.filetap.com