Hello again
"About the firmware upgrade, could I simply do that this way, install windows onto the drive and then run the OCZ Toolbox as stated in the guide I posted earlier and then just reinstall windows again afterwards ?"
Depends on what version of the firmware your SSD comes with. If it comes with firmware version 1.4, then I'm pretty sure you can flash it if it's you primary drive (IE. non-destructive flash), if it's earlier (IE. a lot of drives still appear to be coming with version 1.3, my 128GB did last week) then it's a two stage process and the first flash "is destructive" (IE. will wipe your drive!). In this case, you would really need to use the LINUX based tool/s that OCZ recommend.
see
http://www.ocztechnology.com/ssd_tools/OCZ_Vertex_4_and_Agility_4/
and pay VERY CLOSE ATTENTION to step 2. that says "Shutdown and restart the system" this does not mean just restart your system, they do DEFINATELY mean shutdown your system (in fact I would switch off at the mains and leave it 5 minutes) before re-booting. Not being funny when I point this out, but a number of folks have got themselves into trouble by just doing a system restart between flashes.
To be totally honest, this is so much easier if you first connect your SSD as a secondary drive to an existing system.
They also recommend that when using the toolbox, that you use the standard MS AHCI drivers that Windows 7 installs by default. If you want to try the Intel RST drivers, install them at a later stage. Though to be honest, I had no problems flashing my drive with RST 10.6.0.1027 installed.
Connect your SSD to the first SATA 6Gb/s port (the grey ones). Connect your other drives to any of the blue SATA 3Gb/s ports.
PS. If your mech HD's only have molex power connectors, then these must be pretty old (time to replace maybe?). Though maybe I've got the wrong end of the stick here, is it that your PSU only has molex power cables and no modern SATA power cables? If so, then you can get molex>SATA power cable convertors.