After you have cloned everything from your old drive to your new one and it boots successfully, you don't need Macrium Reflect unless you want to clone a drive again.
I'd sell the Q6600 system and save up for a Dell Optiplex with a Sandy Bridge i5 or i7. I bought one with an i5-2400 for $50. Just needed some ram and an SSD. Perfect media PC for around $100. Add your 550Ti and it will be a decent little rig!
I used Macrium Reflect to clone the HDDs to SSDs on a Dell Optiplex 9020, 790, and 390. It only worked on the 9020 and not the other two. All 3 of the clones took about half an hour, and all of the partitions were the same size. Just on the Dell Optiplex 390 and 790 they won't boot. They both...