Hotshot, this was asked many times. Let's make the situation clear.
Typical 256B intro, like ZMORA, is a DOS program, which has no special requirements to run.
hardware:
any PC with standard VGA graphic card and processor equipped with FPU
(just can be slower on older computers)
software:
DOS, Windows XP or older
(no libraries etc.)
Problem appears in Windows Vista - this system displays the message you posted, and you will not see the intro. Some ugly drivers or other villains can also disable 13h mode under Windows XP.
In such cases, there are some ways you can watch 256B productions on your machine:
1. Use DOSBox emulator. Unfortunatelly, many intros are very slow there, even if you setup max CPU usage (in DOSBox.conf: core=dynamic cycles=max). Additionally, DOSBox is 286/386 compatible, so some intros using newer instructions will not run (eXcentricity, Blub! II ...).
2. Burn intros on CD. Boot your computer with some CD that will start DOS environment (Win98 install or something), change the CD and watch the whole night.
3. Setup some virtual DOS environment. I can't give you any accurate tpis about it, while I have real MS-DOS 6.22 installed normally.
By the way, is there anybody using Windows 7? Any experiences with 256B intros there?