I have that Perc 5i Card working with 7 x 1tb Samsung F1 drives in raid 5 (Raid 5 with a hot spare)
Works well. No hassles.
Couple of tips:
1/ You need:
The Perc 5i Card - £81.35
Battery Backup Unit - £12.49
Cable for Battery Backup - £16
2 x Cable sets for the unit itself - £13.72
(The ones you need are: SAS Controller 32Pin to 4 x SATA HDD Splitter Cable x 2)
(Those four items are an ebay jobby)
These heatsinks:
Zalman ZM-RHS1 Silent VGA RAM Heatsink Kit - £8.04
http://www.overclockers.co.uk/showproduct.php?prodid=HS-014-ZA
This fan:
Akasa AK-160 BL-S 40mm Blue LED Fan - £3.44
http://www.overclockers.co.uk/showproduct.php?prodid=FG-030-AK&groupid=701&catid=57&subcat=818
I just stuck the fan on top of the existing heatsink, and and seems to work well.
I put the heatsinks on the chip next to it, that also gets hot. 1 minute job.
EDITED to add in what the parts cost me in June 2009 - In my case £135.04 for the whole Perc 5i setup.
2/ You are going to also need some nail varnish to do the chip mod you will read about if you do a hunt for 'Perc 5i mod' on google and take a look at the top post. (Read that thread its gold)
Easy enough.
This stops the card from rejecting certain motherboards (it is a server card for dells)
3/ Once you have the hardware configured you need some software:
1/ The dell software to update the firmware
That lives here:
Description: Perc5/i integrated firmware 5.2.2-0072
http://support.dell.com/support/dow...&servicetag=&os=WNET&osl=en&catid=-1&impid=-1
(You will have to configure the card in the bios on bootup. Reasonably self explanatory when you get that far)
I stuck with the Dell Firmware rather then the LSI firmware. The LSI one is supposedly faster. However, when you read that thread I suggested, you will find that a lot of people have weird issues with it. Personally, I can't be arsed with the hassle. The Dell Firmware seems plenty fast to me. And that is what the card is designed for specifically (Incidentally, this Perc is on a Windows 7 - 64 Bit RC1 - Build 7100 system and works fine)
The read speeds on HD Tune Pro were:
Minimum :482.9 MB/sec
Maximum :564.4 MB/sec
Average :518.1 MB/sec
Access Time:11.9 ms
Burst Rate :282.7 MB/sec
CPU Usage :-1.0%
(Doesn't seem to want to do the 'write' test for some reason? Comes up with
'Writing is disabled. To enable writing please remove all partitions. Please check the manual for more information'
Anyone know if I am doing somnething wrong?)
2/ LSI Mega Raid Storage Manager Software (to check on the integrity of the array and make some tweaks if you so desire)
http://www.lsi.com/storage_home/products_home/internal_raid/megaraid_sas/megaraid_sas_8480e/
Right. Thats a weeks worth of research right there.
Just did this myself.
Its worth the hassle though. (And you don't even have the hassle

Thats seriously the steps to take. First time I have seen that little lot written in one post.
I now have a nice fast raid 5 array. I went for the hot spare option as well. So even if a drive dies, it will be rebuilt automatically while I send off for another.
I have had it running a couple of weeks and all works well.
Even simulated a blackout the other day by pulling the plug (to test out a UPC backup device), and no hassles.
I have this running on my main PC.
If you are looking for a backup solution, you may be better off doing what I did, and get a separate box, and set up windows home server. That works great. The backup is literally, set up once, and forget it forever. Mine backs up the main machine every night automatically. No need for a perc 5i card for that one, because the software takes care of that. You just add a load of hard drives of any size, and it figures it out. Windows Home Server is a nice piece of kit.