Can geforce 8600 run on 300w psu

I have dell inspirion 530
Intel® Core™2 Duo Processor E4400 (2MB L2 Cache,2.00GHz,800 FSB)
320 GB hard drive
1GB Dual Channel DDR2 SDRAM at 667MHz- 2DIMMs
16x DVD -/+ RW drive
128MB NVIDIA GeForce 8300GS
No sound card and floppy.

I got a good deal on this, and up grade the video card by my self after I got them. I have my eyes on MSI geforce 8600 gts oc. The problem that I fond out (I did not think this when I bought the pc) is power supply is only 300w. MSI 8600 need minimum of 350w.

Then I look around for other 8600 that only need 300w psu. I found this Leadtek has one:
http://www.leadtek.com/eng/3d_grap [...] id=1&act=2

“A minimum recommended 300W system power supply (with 12V current rating of 20A).” I look the label on my power supply:
Output : 300W +/- 12V / 18A
I am not very good at electricity, anyone know what is this mean?
Is this will work or not?
Can I still get the MSI knowing the recommendation is 350w? I don’t want to change the psu, yet. I just got this last week.

Thank