The Battle of PSU and GPU !!

this week I decided to upgrade my GPU with the Sapphire Amd 7750 OC edition
( http://www.sapphiretech.com/presentation/product/?cid=1... )
and until the last minute,I assumed it was all simply plug and play since I knew my PC had a 450 W PSU installed but then I accidentally discovered that things were more complicated than they seem!! --> http://i.imgur.com/61dN3.jpg (psu specs)

Firstly the system requirements mentioned on sapphire's official website say that their 7750 requires a min. 400 W PSU but they don't say whether I need to connect it to the PSU via a 6 PIN pci cable or not.. because if it does need to be connected then I have a little problem...,my PSU doesn't has a 6 pin PCI .. it only has one Molex 4 pin connector --> http://i.imgur.com/jdbqN.jpg which seems to be shared by the DVD drive too --> http://i.imgur.com/CsaxQ.jpg

I even shabbily ran one of those standard PC power consumption tests,it said my PC uses 257 W out of 450....
So my question to you,is this PSU enough for the mentioned card??plz give me a green signal because if it isn't then I'll have to spend another 50₤ on the PSU  

My general PC specs
AMD X2 Phenon,3.1 Ghz
1x4gb DDR3 RAM
SATA 7200 RPM 500 GB HDD
1x19" LCD Monitor
No additional coolers or nuclear reactors attached!!