I wouldn't call a 6 core CPU you can clock to 3.8Ghz mid range.
If you ask me if going with a i7 for $100 more is not worth it. Either choice is perfectly good though
There's not much to upgrade. Overclocking your CPU is about it.
Value wise nothing makes much sense for you.
If you get an SSD that will make everything super speedy but as for CPU or GPU upgrades not much to spring for.
That's a tough one. I'd probably nab a x6 1055T (95W) that comes out in a few weeks. [Check your CPU compat list when it launches
http://www.msi.com/index.php?func=prodcpu2&prod_no=1333&maincat_no=1
Then see if ATi flips up anything at the end of this year.
If I wanted to save a bit I'd get a 635 and overclock it.