Acronis true image should do the trick to copy the RAID 'drive' to the 1TB.
For that price, a second hand 4850 or 4650. You could see about getting a 5770, but you might not have enough power for it at full load.
CCleaner could clear a bit of space. I also prefer spacesniffer to windirstat
The two should be compatible. Make sure your test system with both interfaces has all of the bios options set properly. I'd assume you...
Gparted comes on all ubuntu discs and many other distro's i'd imagine. Easiest way to do it imo.
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