I'm quite certain it is the psu as it had powered my computer when i only had one 6pin pci connected to my graphics card. When I realised my mistake i plugged in the second 6pin connector to my computer and it wouldn't turn on though all my fans and lights were working. I have read that Thermaltake has been known to actually deliver less watts than what is advertised. I also checked online and found that other people had similar issues and the problem was the psu.
Not surprising that a Litepower 600W wasn't strong enough for your system as I think it is highly unlikely that it is high quality.
Your system doesn't require any more than a high quality 450W PSU with two PCIe connectors. So I would actually recommend the Antec Truepower New TP-550 http://www.msy.com.au/product.jsp?productId=4932
As it is a step above all the listed options in terms of quality and performance, only ~$5 more expensive and it is more than enough for your build.
If it has to be one of the four you've listed then I would prioritise one of the other Antecs. The Antec Earthwatts EA-650 Green is probably just about worth the extra $6 over the Antec VP650P, even though the differences between them aren't great.