The Nintendo Game Boy Advance SP ($99.95 list), a sleek innovative update to the wildly successful GBA, is due to hit North America on March 24. Over 11.7 million units of the original have sold in the US and more than 23.9 million worldwide, accounting for almost 30 percent of Nintendo’s hardware sales. From the attention we received using the GBA SP in public, we think the new design might be even more successful…