Can i use the lcd display from my gateway profile 4 all in one

It is yours, so sure you can use it or is it "may I use it"  

Okay... Joking aside, we need to know what the "use it for" is. TV? Monitor for another system, etc.

You can't. Profile 4 does not have video in capability.

I'm doing the same and this was helpful as it confirmed that the gateway one has no input video port. What I did was used Remote Desktop from my Gateway one to my laptop (small display) and life is great. Good luck!

You can't. Profile 4 does not have video in capability.

Where to use it?
Advertising player Applications
Advertising player is a kind of multimedia advertising and public information distribution system, because of its demonstrated ability to express the content, and therefore it's suitable for almost all public places:

Building multimedia information broadcasting system.
Residential elevator hall, the elevator box, residential building entrance; Business Building lobby, etc.

Moreinfo: http://www.shiningdisplay.com/products.htm

Yes, monitor for a next system

my Gateway profile has a cd drive ......can i change it a dvd drive