Actually, Attila getting the 8051 talking to an ISA VGA card is not very hard at all. Once you got the card initialized for 640x480 character mode like a standard PC does on start up you would have a nice display that could give you 25 rows of 80 characters per row. The software it takes to run the board after initialize is simple and standard. What will vary to some degree is what it takes to get whatever VGA controller that is on the board to initialize. That code requirement will have variation dependant on the controller chip. Some help could be obtained by looking at the source code for a VGA BIOS (which of course would be written in 8086 assembler).

There is a rather good book to get your hands on... Programmers Guide to the EGA and VGA Cards> by Richard F. Ferraro (Addison Wesley) which would provide all the technical detail you would need to get the board initialized. I have the second edition whilst the above link points to a source for used copies of the 3rd edition.

You may also find the following collection of links useful:
http://www.epanorama.net/wwwboard/...12234.html
http://www.eio.com/public/micros.2001/date.html
http://webpages.charter.net/greener/electronics/
http://www.hantronix.com/down/3224app.pdf

Michael Karas