I think the time to upgrade has come since my gpu can barely stand new games nowadays. I use my pc mostly for games and movies, sometimes for CAD modelling. I'm using 23" LG M2352D-PZ IPS monitor.
That's my current build:
CPU: AMD Phenom II X4 955
GPU: EVGA GeForce GTX 260 SSC edition
MOBO: Asus m4a79-T Deluxe
RAM: OCZ ddr3 (2x 2048 MB) 1333 MHz Reaper
HDD: Western Digital Caviar Black 640 GB
PSU: BeQuiet Dark Power P7-PRO 750W
CASE: NZXT Tempest
CPU COOLER: Noctua NH-U12P SE2
I run the Gigabyte GTX 670 Windforce factory OC. The thing is amazing. Has not blinked an eye at any game I have thrown at it so far.
Gonna be hard to get a decent SSD for the price difference between a 660 and 670. They are still not that cheap for any decent size capacity. While this is not an indication of the quality of all SSDs. I have had 2 fairly priced ones, and both have had major problems. Several others in my current guild have also had issues with them.
IMO, until they become more stable. You are better off buying a better GPU over saving a few seconds on load times. =P
Uhm your CPU is going to bottleneck a gtx 670 for sure. So you won't see full performance of it because the cpu is going to hold back. Games like minecraft you shouldn't have a bottleneck at all so it varies from game to game.
You can reduce the bottleneck by overclocking your CPU which should make a big difference in FPS.