Vista - USB HDD dying

Hi All
Help!!
Apologies if this has been posted before, but I need an answer and I am sure some one has it.

Running Vista 64 Home Prem
ASUS P5Q pro board
Intel 2.4 quad processor
8gb RAM
DVD & CD-RW
FDD
5 internal SATA HDD, 2 set as Mirrored RAID Array
3 external HDD's 2x Maxtor 1tb and 1 x 350gb Sumo - USB 2 connected
Various other USB items and one 7 port hub

Problem:

Cannot connect or power up more than one external drive at a time, if I do, Vista 'hangs' or asks for USB device driver - as these are plug n play peripherals - no drivers.

or

External drive comes alive then hibernates after a short time on awakening - Vista looses connectivity with the drive. In explorer is idtenifies the drive as 'local drive' click on this and it then tries to re-format that drive.

I think it is a driver issue but cannot nail down the problem.

Have downloaded KB941600 x 64 but Vista won't allow install as it 'is not suitable for my system' marvelous.

Driver detective? Waste of time and money in my opinion - could update USB Hub drivers as these are proprietory supplied - Microsoft I pressume. So, left with achieving backups to external drives by plugging one at a time executing backup and moving to the next drive etc. Pain!!

Any ideas would be most appreciated thanks.
Oh PSU 700w OCZ