How full is the drive - Max Usable space for a 250 gig SSD is around 180 Gigs ( 250 formated = approx 222 giogs - 20% = 178Gigs).
Are you using the Intel sata II port with the latest Intel driver, or the 3rd party Sata III port? NOTE: the agillity III is a SATA II drive in a sata III wrapper - that is it does NOT perform any better on Intel sata III port than when on a Intel Sata II port.
Can run AS SSD (don't bother running the Benchmark - (Unless you want to be dissapointed), but check the "driver" Should be iaSTOR which is slightly better than default msahci.
Windows WEI not a good benchmark, but You indicated it appears to be slower - Much more important fact.
ADDED: Nuke is 100% correct on use of secure erease, and NOT running benchmarks.