PSU recommendation on Upgrade

Hello!

I need your help.

I've decided to do an upgrade on my ancient PC, which is a 4 year old Acer Aspire SA85.

The things I'm upgrading are: GPU, RAM & PSU

I decided to go with a Sapphire HD3650 512MB GDDR3 AGP


This will obviously require a PSU upgrade. My current PSU is an FSP Group inc. with the following amps
+3.3v = 20.0A
+5v = 26.0A
+12v1 = 8.0A
+12v2 = 14.0A
+5Vsb = 2.0A
-12v = 0.8A

The current set up I have is:

Mobo: Acer E661FXM
CPU: Pentium 4 524 Prescott @ stock 3.066Ghz
RAM: 512Mb Generic RAM (I intend to upgrade this to 1GB with a couple of 512MB Geil 400MHz DDR )
HDD: 1 SATA 7200RPM HDD, I may add another in the future
1x CD drive & 1x multimedia bay

Basically I need help deciding on a PSU.
I have been looking around and I think this PSU should be more than enough : 550W Corsair CMPSU-550VXUK



This is probably overkill but I just want to make sure it works and won't fail me in the future as I will probably overclock the GPU a fair bit in a few months. Also I'd like run this for a year or two and then turn it into a HTPC.

Any recommendations?

Also recommendations for memory are welcome, but I've already bought the GPU so that's a no go.


Thanks guys.