Replace Default Null Values Returned From Left Outer Join

I have a Microsoft SQL Server 2008 query that returns data from three tables using a left outer join. Many times, there is no data in the second and third tables and so I get a null which I think is the default for left outer join. Is there a way to replace the default values in the select statement? I have a workaround in that I can select into a table variable but it feels a little dirty.

SELECT iar.Description, iai.Quantity, iai.Quantity * rpl.RegularPrice as 'Retail', 
iar.Compliance FROM InventoryAdjustmentReason iar
LEFT OUTER JOIN InventoryAdjustmentItem iai  on (iar.Id = iai.InventoryAdjustmentReasonId)
LEFT OUTER JOIN Item i on (i.Id = iai.ItemId)
LEFT OUTER JOIN ReportPriceLookup rpl on (rpl.SkuNumber = i.SkuNo)
WHERE iar.StoreUse = 'yes'

I would like the Quantity and RegularPrice to default to zero if possible.

That's as easy as

IsNull(FieldName, 0)

Or more completely:

SELECT iar.Description, 
  ISNULL(iai.Quantity,0) as Quantity, 
  ISNULL(iai.Quantity * rpl.RegularPrice,0) as 'Retail', 
  iar.Compliance 
FROM InventoryAdjustmentReason iar
LEFT OUTER JOIN InventoryAdjustmentItem iai  on (iar.Id = iai.InventoryAdjustmentReasonId)
LEFT OUTER JOIN Item i on (i.Id = iai.ItemId)
LEFT OUTER JOIN ReportPriceLookup rpl on (rpl.SkuNumber = i.SkuNo)
WHERE iar.StoreUse = 'yes'

In case of MySQL or SQLite the correct keyword is IFNULL (not ISNULL).

 SELECT iar.Description, 
      IFNULL(iai.Quantity,0) as Quantity, 
      IFNULL(iai.Quantity * rpl.RegularPrice,0) as 'Retail', 
      iar.Compliance 
    FROM InventoryAdjustmentReason iar
    LEFT OUTER JOIN InventoryAdjustmentItem iai  on (iar.Id = iai.InventoryAdjustmentReasonId)
    LEFT OUTER JOIN Item i on (i.Id = iai.ItemId)
    LEFT OUTER JOIN ReportPriceLookup rpl on (rpl.SkuNumber = i.SkuNo)
WHERE iar.StoreUse = 'yes'