It sounds like you haven't formatted the LUN yet.
In the ACU on a windows box, you should have already created your Array and then setup your logical drive. Keep your LUNs under 2TB, which is the limit for ESX. Present your storage to the host (if you're using SSP.)
If it looks good in the ACU, then go back into the VIC, select your host, then click the Configuration tab at the top. Choose Storage Adapaters. Generally speaking, the raw LUN will show up here. If not, click the RESCAN link in the upper right corne. You really can't go anywhere until the storage adapter sees the storage. If it still doesn't see it then i would guess you haven't correctly presented the storage to the host (SSP.) If the adapaters DO see it here, then you can now go to the Storage link and add the storage.Once you're able to ad the storage, you can finish up by formatting the LUN via the wizard.