you need to use recordsets, something like:

(access97 using DAO)
Sub cboYourCombo_AfterUpdate()

Dim sSearch as string
dim db as database
dim rs as recordset

set db = Currentdb

sSearch = cboYourCombo.Text

set rs = db.openrecordset("select * from tblYourTable where YourField='" & sSearch & "')

rs.movefirst

txtFirstTextbox = rs("FirstField")
txtSecondTextBox = rs("SecondField")

rs.close

End sub