RAID tweaking

Running a dual Xeon 900 server with 1GB RAM, 12 18 GB SCSI 160 15K RPM drives. The 12 drives are divided over 2 cages -- 6 drives in each cage. Each cage is connected to one of the 4 ports of a Compaq 5300 Smart Array RAID controller with 128 MB of cache on the controller. Windows 2000 Enterprise edition is running on the server on two a mirrored drive in one of the cages.
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This setup will be used for running SQL Server 2000. My optimum performance presently seems to be with the remaining 4 drives in the cage where the OS drives are located striped 0+1 and used for retaining the database logs and running the other six drives RAID 5. Getting additional drive cages at this time is not an option. I feel like at least two of the drives present are more-or-less wasted (performance wise) and I am figuring that I am going to have LOADS of surplus space.
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Two questions:
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1) I feel like I can remove 2 drives from each cage, have the rebuild the system with 2 4-drive RAIDS, suffer a small performance hit and free up 4 15K drives. Anyone see problems with that?
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2) Anyway anyone can see to squeeze out more performance from this junk? I can probably get another RAID controller, but as I said: getting another cage is not an option.
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. Suggestions, mudslinging comments, and insults are welcome
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. Dave

What form factor is the server? If it will accept internal drives, you can use another RAID card to establish a RAID-1 array in the server and reduce the bandwidth demands on the 5300. If you can't get 2 additional drives, pull 2 from the current expansions, leaving 1 open bay in each expansion for the addition of possible hot spares. You can run each expansion as a 5 drive RAID-5 array, with an open bay for possible addition of hot spares later, or another option would be to run 6 drives in one array as a 1E or 0+1 depending on terminology used. and one array as a 4 drive version of the same. The first option conserves storage capacity while the second will get slightly faster read times. We use a configuration similar to the first on one of our servers. We have a 6 drive 1E array for the OS and apps internally with 2 10 drive RAID 5 expansions for storage.

I'll see if I can give this a try.
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. Dave