Show only values from 2nd Field

I bet this is a common one, but I'm a self-taught novice and new to this forum thingy. I've learned about using "show only values from 2nd field" in value lists, and placing two fields on top of one another, (one unable to be entered) in order to enter the serial/id but see the meaningful data about a record.

It's great stuff but I think my data entry screen sucks for my users because I have to stand over their shoulder and say things like..

" Now hit enter" and "Now hit enter again" and "no don't type in that field with a strange number showing, click somewhere else then click on the field again to get the menu.." and "Type faster, if you stop it starts again.." (referring to the auto enter function), "trust me I know what I'm doing ..this is efficient you'll see etc."

It seems to work better on Mac than Windows but the problem is still there. I know I could use the pop up menu thingy instead of the drop down list, but then it won't allow the auto enter option and with 2,000 of the buggers to choose from it would take forever to find the person you want.

Any hot tips for a fast serial/id input using a value list with lots of options?

Phil