When replacing my LAIM gasket and water pump on my 1998 5.7L Vortech I completley drained my cooling system. After completing the repairs, I refilled the system with 50% regular old hose water along with 50% Dexcool. Am I asking for big trouble if I don't flush and refill with DISTILLED water? Thanks for the advice ahead of time.

Depends on what kind of water in the old hose.
Distilled water is always safe.
Good Luck

A main concern is the minerals and other "contaminants" found in residential water supplies that can wreak havoc on your vehicle's cooling systems. Distilled water is fairly cheap so I look at it as an extra "insurance policy" when maintaining the cooling system.
Some parts of the country's water supply is very "hard" with calcium and other large quantities of dissolved minerals which can clog a radiator's passages over a period of time.