yeh i know there is a recommended list but isn't it a bit old. Anyway, i bought an NZXT hale 650W PSu but broke within a week So I have £80-£100 pounds to spend on a modular PSU. Just to check that 650W is about right. Core i5 2500 Asus P8P67 2x2Gb Gskill RipjawsX GTX 460 SE (didn't realise until it was too late about the SE bit ) 2x120mm 1000rpm fans 1tb Samsung f3 HDD
I don't know the HX650 personally, but someone was complaining about the quality of the cable connectors - easy to break, apparently. I'd recommend going for something with the longest warranty - as you say, they don't change much, and a PSU failure is such a pain, you end rebuilding the whole PC! Coolermaster do a 5 year warranty on the modular SilentPro 650 which you can get for less than £80 I think.
I have a HX620, which appears to be discontinued judging by a quick google, but i kinda assume that the 650 is the sequel, and if it is anything like it will be fine. No complaint about the cables. And a decent 600w-ish is more than enough for what you have. My 620w has powered an e8500 @3.8Ghz and two oc'd 4870's and now powers my Phenom 965BE @3.7Ghz and two oc'd 5850's and 4 HDDs. As you have 1 GPU, 1 lower TDP CPU and probs less HDDs than me you'll be fine. There's such a myth about how much power a pc actually needs, probs perpetuated by mfgr's wanting to push stupid 1000w+ psu's into the mainstream for $$$. Not to say that an SR-2 with a water loop and three 590's won't need that but 99% of users don't. </rant>
Yup, the HX650W is the successor of both the HX520W (which I have) and the HX620W. It's also manufactured by Seasonic, so quality is assured. Regarding the wattage of the PSU I do agree. But in a way the wattage is less "important" than how the power is distributed. These days you want as many amps as possible on the 12V rail(s). I'm currently looking at upgrading to a Seasonic X-560W myself (my HX520W will soon be 5 years old). That should give me plenty of power.