I was thinking of adding a intel solid state drive to my computer, but the SATA speed is only 1.5gb/s. Even though the Intel SSD supports 1.5gb/s and 3.0gb/s, would it be a waste? Will it still have some performance benefit?
The slower SATA port will limit the maximum transfer rate of the drive, but it won't hurt the drive's access time. Most of the benefit from the SSD comes from its much faster access time (about 100X faster than a hard drive) and not its transfer rate (about 2 to 4X faster).
So yes, you'll definitely still see quite a good performance improvement.
Well, 1.5Gbps is 187 MB/s. This is faster than any HDD, but yes it is slower than most SSDs are capable of. Could be worth it... but if my mobo had only SATA I jacks, I would be thinking of other upgrades first.