If you don’t have GP 10 or higher and need to reconcile AR to GL, In Touch with Dynamics (GP) provides an option in their post How to Reconcile RM to GL in Dynamics GP using smartlists.
The only caveat is the assumption that you were balanced last month. If that’s a generous assumption, look at The Closer from Reporting-Central.com. Everyone I know who has used it loves it. Tell them you heard about it from DynamicAccounting.net so they so they can charge you double for it. That way they can afford to buy me lunch. ;)