1. If you mean the RAID BIOS message that pops up, usually there is no way to stop that unless there is a motherboard jumper to disable RAID.
2. 232GB is normal (formatted) for a 250gb drive.
Drive manufacturers rate drives in "Japanese megabytes" (there are other names also) which are just 1,000,000 bytes = 1MB. In reality, 1MB = 1,048,576 bytes. So you only get 95.36% of the rated capacity. 250 GB (in Japanese megabytes) = 238.4 GB (in raw unformatted real megabytes). Figure in a couple gigs for the filesystem, and thats about right.
Desktop machine: 2 x Opteron 246, Asus K8N-DL, 2GB PC3200 ECC Reg., XFX GeForce 6600GT, 74gb WD Raptor, 2 x 19\" LCDs, Windows XP x64
Server machine: Intel P4 3.0GHz 2MB EM64T, ECS i865pe, 1GB PC3200, 36gb WD Raptor, Windows Server 2003
Laptop: Dell Inspiron 9100 (Intel P4 3.2GHz 1MB Prescott, i865pe, 512MB PC3200, Mobility Radeon 9700, DVD+R/DL Burner), Windows XP
Linux: P3 450Mhz, 386MB ram, Slackware 10.1 (Running mySQL/Apache)