Yes, it would be worth upgrading.
You have two options. First, you can install a SATA 2.0 3Gb/s ssd. Second, you can install a SATA 3.0 6Gb/s. The SATA 3.0 6Gb/s ssd's are backward compatible with motherboards that only support SATA 2.0. However, there will be a performance hit. SATA 3.0 drives will be limited to SATA 2.0 performance levels. For the typical user the difference usually is not noticeable.
For a SATA 2.0 3Gb/s ssd I recommend the Samsung 470 series. The 470's are problem free.
For a SATA 3.0 6Gb/s ssd I recommend the Crucial M4 series. The M4's are popular and relatively trouble free.
At the moment I do not recommend ssd's with SadForce based controllers. The SadForce based ssd's have ecperienced more than their fair share of problems. OCZ has been particularly hard hit. Recently during a 6 month period OCZ had to issue 5 firmware updates to resolve problems.