is there a way i can take....a game like doom, and make it possible to play it on a computer without having to install it?

get a u3 flash drive

www.u3.com

Don't the programs have to be am made to run on that device?

for example, i couldnt install WLM and expect it to run.

or am i wrong..........

WLM runs fine without registry keys, it just won't remember your settings

I simply archived my WLM folder in a RAR archive and made a SFX out of it, making it extract all the files to the Temp directory on the computer and then starting msnmsgr.exe

Games is another story, some games might work without registry keys and some won't, also some might be specifically configured for the hardware where you installed it on, causing it to crash/not work on the other computer. You'd also need a No-cd/dvd crack so circuimvent the cd/dvd check.