Although MERGE isn't available in 2005 you can still replicate it to a decent degree. See here for some links.

Since you're not letting on what type of load this is (data warehouse, something else) and what data sits in the table (If it's a fact table with FKs to surrogates in Dimensions then it's different than if it's one of these catch-all "reporting" tables I've seen on my travels and normalising what you have may help) - going purely by what you have said your idea, though workable, will just get slower and slower as time goes on.