First of all, what OS are you running? And what mobo?
Windows 7 has a feature called TRIM, that will help the drive "self optimize." This keeps the drive from "...lose performance as they age/used more,..."
And on Intel based motherboards (X58 or P55 chipseets), the ACHI function also helps, kinda.
My suggestion would be go with a little smaller SSD, say 60-80GB, and get another HDD for data/media. Install the OS and Program Files on the SSD, and all your "data" on the HDD. "Data" could be your libraries like My Documents, Download, Music, Pictures, Videos, etc.