Question : What is the best Raid stripe size and Windows allocation unit size for large files?

We run 2008r2 boxes with 6x2TB drives in a RAID5 config using a DELL PERC6/1 card.
My question is there are several options to choose from for the stripe size such as 64kb which I have read is an overall best and in windows you can format the VD as 64KB as well. I guess this works well but in the PERC6/i there are options for stripe size upto 1MB. Just wondering if I choose 256 or 512 for eg then what would the windows allocation size be? Or does someone have recommodations? On this drive we store 30GB system images!
Thanks all in advance for you help
Andy

Answer : What is the best Raid stripe size and Windows allocation unit size for large files?

I use 256k stripes on all my box's using virtual machines. Works out well.