The WDC Green did quote a speed of around 5400 - 7200 RPM, vs. the 5400 of the WDC Blue. As for the barracuda, you have to check the spindle speed of the hard drive to make a comparison. Seagate and Western Digital both make good drives; none of their products have failed on me yet.
The Blue is their normal range model and is 7200 RPM. The Green is between 5400 and 7200, probably closer to the 5400 mark. Their Black version runs at 7200 RPM but is faster than both. The green version was designed to be a low power alternative and performs accordingly. I am unsure about the seagate. I would, however, recommend the WD Caviar Black 500GB SATA. Some may recommend samsung spinpoints, saying they are faster and more reliable. The recommendations appear consistent. The only reason I do not is because I have no experience with them (They seem scarce in Canadian retail stores).
Either get a WDC Black series, Samsung Spinpoint F3 series or Seagate Barracuda 7200.12 series, all are around the same price point give or take a few dollars and all give comparable performance to one another
I have a couple of Caviar Blacks, 640gig and 1 TB drives. I can honestly say that while I have no complaints with them, the next drive I buy will be one of the spinpoints.
The WD drives are okay, but I don't think that they are all they are bragged up to be.
Western Digital has served me well so far, however the three drives you have listed are SATA drives, or in otherwards consumer-grade drives, or in otherwards crap/cheap. They can fail on you at any time. If you want reliability/performance, look into Fibre Channel drives. Out of those three i think WD takes the spot from personal expirience.
Corey, i would recommend the WD black, the green series uses less power but the black series performs alot better, im sure there will be a noticeable difference in load times and boot times going with the black over green. Theyre around the same price anyways