Hi, i wanna purchase new grahic card same as i had written on title, and want to know if ill need to purchase new power supplies?

Answer:
The 7600GS does NOT require any additional PCI-E power from an auxilliary connector. You can easily run this card with a 300W PSU. Just make sure your PC's motherboard has a PCI-E x16 slot free!
Answer:
The image on the link below advocates that the Inno3D 7600GS does not require an additional power supply connection. (My Gigabyte 7600GS has a 4 pin molex for additional power). The image isn’t necessarily guaranteed though - but there is no mention in the blurb about an additional connector.

There is mention that a 450-500W PSU is required, with a minimum of 26A available on the 12v rails.

Th Octigen 400W PSU has a single 12v rail capable of delivering 12amps only. There is no chance whatsoever that this PSU will be able to drive the 7600GS.

Mine is able to drive only integrated graphics, a Radeon 9550 or an nVidia 6200.

Scan have a Gigabyte badged 460W PSU with two 12v rails rated at 14A and 15A for only £25.84 - given that the Octigen 400W cost me £19.99 that's excellent value for money - and it will do the job.

It's £30.63 from Dabs, but Dabs have (well it's due soon) a 512Mb X1650 Pro for only £33.25 actually a more capable card than the 7600GS, or if you're still keen there’s a 7600GS (due soon again) for £38.82, but superior would be the 512Mb 8600GT in stock at £40.34

Scan have an array of 8600GT cards, some underclocked, some with GDDR3 but Dabs seem to offer superior value for this price point.

I priced the Inno at £57 from misco - even with the 460W Gigabyte PSU, you should be able to source a comparable card and still come close to that!

Good luck with your build.

Answer:
It depends on whether your existing power supply has a pci express power connector - you could use an adapter anyway, power supply should be fine.

Your graphics card may come with one similar to this anyway;

http://www.thecoolingshop.com/product_in…

Answer:
You need a power supply with at least 20 amps on the 12 volt rail. Your power supply should have a sticker with the rating on it.