Based on the following example URL structure:

mysite.com/mypage.aspx?a=red&b=green&c=blue

Pages in the application use ASP.net user controls and some of these controls build a query string. To prevent duplicate keys being created e.g. &pid=12&pid=10, I am researching methods of rewriting the URL:

a)

mysite.com/mypage.aspx/red/green/blue

b)

mysite.com/mypage.aspx?controlname=a,red|b,green|c,blue

Pages using this structure would be publishing content that I would like to get indexed and ranked - articles and products (8,000 products to start, with thousands more being added later)

My gut instinct tells me to go with the first method, but would it would be overkill to add all that infrastructure if the second method will accomplish my goal of getting pages indexed AND ranked.

So my question, looking at the pro's and con's, Google Ranking, time to implement etc. which method should I use?

Thanks!