Question : Problem: How would you make this Backup better?

Recently our IBM TotalStorage units power unit failed. Instead of going the route of having it repaired without Warranty which is very expensive. I've decided to go a NAS Route.

For a quick fix to get some backups going while we made the decision to which route to take, I purchased a Seagate 500GB Free Agent.

Today I ordered
BUFFALO LS-W1.0TGL/R1 1TB LinkStation Pro Duo NAS x Two
BUFFALO DriveStation TurboUSB HD-HS500U2 500GB x One

So, this gives me two 1TB External Hard Drives and Two 500GB Hard Drives. I've learned how to use VERITAS Backup Exec and back up to the External Hard Drives and the Following is my plan.

Monday, Tuesday, Wednesday and Friday will be Differentials
Thursday will be Full

One External Hard Drive will hold the Differentials and One External 1TB Hard Drive will hold the Fulls.  The 500GB hard Drive will Copy the Friday Full and I'll take that off Site.

All suggestions welcome.

Answer : Problem: How would you make this Backup better?

What I'm seeing is...

2x1TB NAS - one being used for the full backups (I'm guessing the thurday's), and the other not being used.
2x500 GB External HDD's, one being used for incrementals each day (are you overwriting each day or every other day?) and one being used for another full backup on Friday which goes offsite...

I'd add another 500GB for rotation with the offsite drive, as I'm assuming that the other NAS if for actual onsite usage....