This Should Be Simple (marge 2 Queries)

I have one query that returns a list of all debits in a given year/month/cost element: e.g.

Year Month CE Debit
2007 6 111 100.00
2007 6 153 150.00
2007 6 157
2007 6 294 75.00

and another that returns a list of cost element budgets: e.g.

Year Month CE Budget
2007 6 111 500.00
2007 6 120 75.00
2007 6 153 200.00
2007 6 157 120.00

So you can see there could be budgets with no debits against them, and there could be debits with no budget (either could be zero or null). What i want is to merge the two so that I return ALL possibilities: e.g.

Year Month CE Debits Budget
2007 6 111 100.00 500.00
2007 6 120 75.00
2007 6 153 150.00 200.00
2007 6 157 120.00
2007 6 294 75.00

For the lif of me I can't get this to work - I can get all budgets, or all debits, but not a merge of both. Can someone please suggest a solution or point me in the right direction?