I would have rather gotten an X3. It would've been cheaper, and could have unlocked to a quad core, just more stable and with a higher clock speed. Of course, had the unlocking failed, you'd still have a triple core instead of a dual.
You also shouldn't have spent $40 on a DVD burner. They can be had for under $20.
The first thing I'd recommend upgrading is the PSU. 500W for $20? That's a really crappy PSU. In fact, I'm kind of amazed you've got it working with the overclocking.
Anyway, before you do any additional upgrades, replace it with a quality unit. I'd look at a 550W or 650W from Corsair, SeaSonic, Silverstone, Antec or XFX. They're all about equal, so get the cheapest of that group.
I'm not getting the aftermarket cooler question. You've got a healthy overclock (and unlock) on the CPU with an aftermarket cooler? That's pretty dangerous. If that's the case, make this the first purchase. I'd look at the Scythe Mugen 2 Rev. B (SCMG-2100) for about $40. If that's too expensive, the Coolermaster Hyper 212 Plus is around $30, but the extra $10 for the Scythe is worth it.
Then, I'd look at upgrading the GPU. I'd look at something like the HD 5770 or GTX 460 if you're not looking to spend too much. After that, I'd probably jump to the HD 6850, followed by the 6870, 6950 then GTX 580. If you go with the 6950, you can flash the BIOS with the BIOS of a 6970, and the card will perform just like the more expensive one. I'd say it's the best value right now because of this little feature.
I'd avoid the other two upgrades for a while. Useful sizes of SSDs (i.e. 120 GB+) are still really expensive at about $200 for the good ones (OCZ's Vertex 2 and Agility 2, G.Skill's Phenoix Pro). I'd wait for that to drop under $150 before seriously considering a SSD.
BluRay drives are completely pointless in PCs right now. All you get is the ability to play BRs. There isn't a PC specifc use for them. The only time I'd recommend getting a BR player (I never recommend burners, no reason to) is if you've already bought a lot of BluRay movies, but don't have a BR player already, and have the computer hooked up to your main TV. Since that is never the case, don't bother with BR. Wait until a computer-specific use develops, or they get dirt cheap. I'd probably wait until you're only paying a $10-20 premium over regular DVD burners, so wait until they get down to about $30-40.