Is the 350W just a gerneric PSU?
the 350W is a Raidmax brand.
the 20+4 pin connector allows you to connect it to motherboards that require both 20 and 24 pins, it just makes the power supply far more versatile.
Being 4 years old your PSU likely wont output what you need so its best to wait for your new one to come in.
Right now my 350W PSU runs a P4 2.8GHz single core CPU @68Watt, 1 stick of 512mb PC3200 ram, a total of five Fans, an AGP slot ATI 1650Pro 512mb video card, two DVD-Drives, and one 160gig Hard Drive. and 1 PCI tuner card.