I have to agree with Ol'89r here...
You already know what you are going to do.
Just what you learn, by figuring out if indeed it is a fixable ride or not, is invaluable.
If all you want to do is ride, then I'd suggest finding a running ride and go for it.
But, if you are really looking down the road at a nice new dirtbike, I would think putting some real love into the old beater, along with a few busted knuckles, would show the Mrs. that you truely have a passion for these contraptions. Maybe it will cause her to sway in favor of you actually throwing down the coin for a top shelf bike.
Wives are funny, man...they are always grading you in some fashion or another...
(lol) keep that in mind. :)