Need advice on buying a new power supply.

I have a comp that I need to buy a new psu for.Its about 2 years old. I want to be careful what I buy because I wan to make sure that it has all the power connections I need. Here are the specs of my comp:: AMD 3100 sempron 1 gig of ram pny geforce 7600. The video card is the main reason I need to upgrade. My psu is rated a 250 watts and I keep getting a popup from a nvidia program that tells me my comp needs at least 300 watts to run this card. I can get a 500 watt psu on newegg for cheep. That way I will have plenty of headroom but again I want to make sure it has all the necessary connectors to power my comp and its devices. Thanks in advance for the help.:major

 

Hotrod,

Newegg has pictures to show you what the PSU has for plugs.

 

Thats not the problem I have NEVER upgraded my psu before and I don't want to get the wrong one. I am not sure how to figure out what connectors I need and how many of each type I will need. My other concern has to do with compatability. I dont think thats a problem but my comp is over 2 years old and I want to be carefull.

 

What brand PC ? Make & model?

Cheep PSU's are usually just that, Cheep, Ya get waht ya pay for
Sometimes Less

 

I have a compaq presario. With a. sis mobo.

 

:confusedLike I said I have a compaq presario with an SIS motherboard and I want to make sure that it has all the connections to run my board, graphics card, dvd, and hd. I have never tried to upgrade my psu before. So I am trying to do it right the first time if that is possible.