Definitely yes to the SSD. I just built a new rig, but I could have held out longer with my old rig (see sig). The SSD made a big difference in the old rig for the short time I had it in there.
Main PC: Asus P8Z77-V Deluxe ; Intel i7-3770k ; GSkill Ripjaws X Series 16GB DDR3 2133 (2x8GB) ; Seasonic X Series X-1050 PSU ; Corsair H100 ; EVGA GTX-670 ; Mushkin 240GB SSD system drive
Old PC: ABIT IP35 Pro ; Intel Core2 Quad Q6600 ; Patriot 6GB (3x2GB) DDR2 800 RAM ; EVGA GTX480 SC ; Antec P190 Case ; EnzoTech Ultra120 CPU Cooler