Need to know how to write a "conditional query" in Access 97? : o /

Ok...i have a problem ...i have a query that generates a calculation in a field called Salesman Overage.  Below is the formula for the field:
Salesman overage: [Commissioncalc]-([Cabinet Net]+[Fin Mat'l])

This works fine as long as JobCost < ContractPrice.

What i need to do is be able to write something that says If the JobCost > Contract Price then i need it to run an alternate forumula that looks like this:

Salesman overage: [Total]-[ContractPrice]

Is there some sort of way to write this as a conditional if then statement in the query in that field?  In other words in the field where the query has this:
Salesman overage: [Commissioncalc]-([Cabinet Net]+[Fin Mat'l])

Replace it with something that would be equivelant to this:

If jobCost < Contractprice then
Salesman overage: [Commissioncalc]-([Cabinet Net]+[Fin Mat'l])
else
Salesman overage: [Total]-[ContractPrice]

I don't want to have to create any additional fields for this.  I'm very new to access so please be specific...Thanks!!

BTW..I'm working in Access 97