Is your 1 T drive partitioned?  Once you get into very large drives, I found it a good idea to partition them.  I keep my OS in one partition, my apps in another.  My runtimes are on a separate HDD.  I'm still old school and keep Poser and my external runtimes well away from each other even though I haven't had Poser take down my externals since Poser 5.

You might want to take a look at some of the Partitioning software out there.

If you can't afford it, check daily with Giveaway of the Day

giveawayoftheday.com

You can find a lot of useful software there.  The daily giveaway is free.  Only catch is, if you have to reinstall the OS, you lose the app.