This is one of those questions that is really hard to answer conclusively. Historically speaking it proved to be a mistake because of how it turned out but that doesn't mean it was a bad idea from a strategic point of view. Had the Wehrmacht been able to achieve their strategic goals it would probably have been a good idea but this is "what if"-history.

What can be said is that the military objectives of the invasion and the overall strategy was sound at heart. Germany needed much of the resources available in western Russia (oil, grain etc) and picked an opportune moment to attack. It didn't work out in the end for a whole host of reasons but that doesn't mean that the plan was bad.

To fully understand why Germany invaded the Soviet Union (political ideology aside) one needs to understand just how enormously dependent Germany was on Soviet imports prior to 1941. From Feb -40 to Feb -41 Germany recieved:

1,600,000 tons of grains
900,000 tons of oil
200,000 tons of cotton
140,000 tons of manganese
200,000 tons of phosphates
20,000 tons of chrome ore
18,000 tons of rubber
100,000 tons of soybeans
500,000 tons of iron ores
300,000 tons of scrap metal and pig iron
2,000 kilograms of platinum

This is just in a 12 month period, in truth, Germany depended on Soviet trade, and Soviet imports on behalf of Germany, as early as 1934. Without the resources provided be the Soviet Union I find it highly unlikely that Germany could ever have waged war against anyone for an extended period of time or built up the army it did. Being this reliant on a single source of resources is dangerous, this would have been well known by the german political and military leadership.

Basically, Soviet provided the resources Hitler needed to invade both west and east. Feeding the German Eagle: Soviet Economic Aid to Nazi Germany, 1933–1941 by Edward Ericsson (sp?) is a great book on the topic.