Thinking about IBM's Roadrunner, comparing it to mine

How much time would it take for a supercomputer to break one of your passwords if you used AES-256? Encrypted RAR files and a lot of secure internet websites use it.

My computer which is an intel Core2 Duo E8400 can try 240 passwords per second.

I used Sandra to see how many flops my computer did, it ranged at above 25-30 GFlops. IBM's Roadrunner does 1,105,000 GFLOPs.

Which means it is equal to around 40,000 units of my pc.

Using this neat online tool I found that a 7 character password (upper and lowercase and digits) would stand a 5 day brute force attack by Roadrunner maximum.

8 characters would stand 9 months.

9 characters 44 years.

10 chars 2.6 thousand years.

15 chars 2.4 trillion years. So if you use a 15 character password (uppercase, lowercase and digits) you are pretty safe until they invent functional quantum computers.

The danger is here: If you use a normal 7 character password made of lowercase letters, the Roadrunner will crack it in less than 14 minutes.

The numbers are not accurate at all. They change with the size of the file, and different types of bandwidths inside the computer(s) (and between the processors in the supercomputer) come into play.

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Update:

I found out that the size of the file is extremely important in cracking it. My computer was able to run 16 thousand passwords per second with a sub kilobyte file.