question about a 9500 gt

I bought a 9500 gt but according to one review I recently found of a 9500 gt:
http://www.newegg.com/Product/ProductReview.aspx?Item=N82E16814130395

"The box says that the card requires a power supply with a 12V rail that makes 18A. My Antec 550 Neo runs it easily."

will this hamper my performance? I am not using more than 220 watts already on my system so I have a lot of room and this card only utilizes 50 watts, but at the same time I only have one 12V 15A rail.

my psu: http://support.gateway.com/s/POWER/102544/102544sp3.shtml
It is +12v/15A +12V/.08A as output
+5V/30A +5VSB/2AQ
+3.3V/28A

I am missing around .5 of an amp when I take this test of my system:
http://www.extreme.outervision.com/secure/psucalculatorpro.jsp

they dont even list the 9400gt or the 9500gt and the 8600 gt might be a bit lower requirement amp wise so Im really struggling mentally now. I used the $1.99 paid version of that calculator cause it shows Amp output on the current system. But I am not exactly even sure if my computer has a Manchester or Toledo processor. I already disconnected a 56k modem from it I am that paranoid for the extra point of an amp (although Im not even sure the modem uses it) and am already thinking of disconnecting the media card reader. Here are my specs:
http://support.gateway.com/s/PC/R/1009484/1009484sp3.shtml

I also dont know what exact type of fans (I have 2) it uses but I guess it is the lowest or smallest version they have listed. It also only has a SATA1 hard drive lsited but I have a SATA2. can you guys imagine what kind of **** luck I have??? THe one card I bought out of all the choices for low profile cards isnt listed on the extreme psu test thing. It isnt even part of the options.

You will be fine with the Neopower and the 9500 GT. The 18A recommendation is for the combined amperage available on all 12v rails. I'm not sure of the combined amperage of the Neopower 550, but with 3 18a rails you have more than enough for the 9500GT.

that my computer's case isn't low profile but that the 3850 simply did not fit in the case? I cannot find any info about my computer online or on gateway's site that it is low profile. WHen I go home later Im gonna try putting in the old 9800 pro in the motherboard (but not put it in any slot since I dont have an agp slot to see if it slides down) this way i think Ill be able to tell. because if I open the 9500 gt form newegg and return it after finding I dont need a low profile I might have to pay restocking fees.

I only have one positive 12V rail and I dont have a neopower. Mine is only 15 amps.