speed wise, will the speed of a raid 5 using the perc, be the same as using raid 0 using linux software raid?
If the number of drives is the same, RAID0 will always beat a RAID5 (at least for lower numbers of disks - I have heard that RAID5 can scale better than RAID0, but this is more to do with controllers optimised for large RAID5 arrays than the underlying technology, and is hard to predict).
If you assume the controllers don't limit you (which is actually a reasonable assumption for most decent hardware RAID cards & Linux Software RAID0, at least as far as personal use goes), then RAID5 needs 1 more disk than RAID0 to offer the same performance.
The amount of cpu overhead involved in RAID0 is so small that onboard & software solutions can be considered just as fast as dedicated cards (especially if caching is enabled on all the systems). Decent software RAID5 has a slight performance hit on writes, but if the cost of the controller is instead put towards faster disks or a better cpu this can be offset. Large software RAID5 arrays can often be read much faster than hardware RAID5 arrays, as multiple controllers can be used which removes a potential bottleneck.