OK. You will get a lot more performance than today even with 4 pairs in RAID-1. Then You have OS an exe’s on first pair and DB on three pairs (that is a total of 8 disks). Each DB-file will then hold approx 5Gb data which I think is to much. Try keep it under 3 GB = More disks. My previous advice with 8 pairs (=16 disks) would give You 2.3 GB in each database file which is perfect and will give You a LOT more performance than today. When it comes to cache You should never enable write cache even if You have a battery backup on the controller. Only use read cache. Putting 3GB Ram wont do any good. You can stay on 1.5Gb. With a cache in Navision on 800MB You will still have allmost 700MB left for OS which should be enough to avoid paging. There is a simple rule with Navision. Allways RAID-1 and a if You want performance: Buy a lot of disks. Dont bother so much about CPU or RAM. It’s all a matter of disk and network I/O.