XFX Pro Core Edition 450W enough?

PC spec:

AMD Phenom II X4 quad-core 945 @ 3.0Ghz (95W)
Sapphire HD7850 OC 2Gb GPU
4Gb DDR3 RAM (2 x 2Gb)
1600 x 900 resolution monitor
640Gb Sata HDD
1 x DVD Drive

Hi all,
Had to RMA an Antec 620W PSU because the cooling fan developed a rattle after a month, and as they didn't have any more in stock I got myself a XFX Pro Core Edition 80+ Bronze rated 450W PSU. I intended to get the 550W, but my mistake. Anyway, I installed the PSU and everything works perfectly. Even when gaming (e.g. Tomb Raider) the PSU only gets slightly warm, stays pretty quiet and there are no issues whatsoever. The card actually recommends a 500W PSU. But I am aware that not all PSU's are created equal, i.e. the quality XFX 450W will outperform other cheaper 500W rated supplies. The HD7850 only consumes 60W more than my original HD7750 card, and that card made do quite nicely with the original OEM 300W PSU in my rig! I perhaps went overkill with the Antec 620W.
Would I be OK with this 450W PSU? Obviously all seems well. I don't intend to overclock anything, and I reckon that the max. total system draw probably won't even exceed 280W, thus leaving decent wattage headroom with the PSU. I will not adding anything else to my rig which will consume more power.

Thanks in advance.