You're not giving a lot of information here, but it looks like a 500 watt power supply. That shoooould be enough to upgrade to a larger card, though it depends on the quality of the PSU and how close it can realistically come to its theoretical maximum power output. A cheaper PSU is going to be less efficient with its 500 watts, basically. But I think you should still be fine.
Also, don't buy a 600 series card. There's no reason to unless you're getting it extremely cheap from a friend or something. Buy a newer card. I haven't been keeping up so much on video cards these days, but I guess the 900 series just came out. Maybe go for a 970?
If it were me I'd buy a new PSU that I knew was reliable and capable alongside a new 900 series card. Your PSU is super important, and it's always good to make sure you have one that will hold up, but it's up to you.
If you were to buy a PSU and wanted something relatively cheap yet awesome, I'd go with one of these.
I've been yearning for a Mass Effect rerelease lately. Their controller support (or lack thereof) and DLC situation on PC is a hassle, and I'd like all three games plus DLC in a nice tidy package. I know it's perhaps not completely in the spirit of the HD remake, but I'd totally play a smoother and higher res version of that entire series again.
Hey, nice. Sleater Kinney joined in on "Rockin' in the Free World" at the Pearl Jam concert I went to last year. I haven't listened to a ton of their music, but I agree that Carrie Brownstein is great, so I should probably check them out.
That's cool, man. If you're looking for a fun and motivating way to get some writing in every day, check out 750words.com. I wrote there for a long long time. Unfortunately it's a service you have to pay a bit for now, but I believe there's a free trial, so I'd recommend trying it out. You can earn badges for your writing, which are an achievement or trophy equivalent, and that's fun if you're into such things. It will also track lots of other stats about your mood and most used words for each day. It provides good incentive to just write, about absolutely anything, every single day.