Upgrading my PSU for a hp computer

HP Pavilion a6607c Refurbished Desktop PC - AMD Athlon 64 X2 4600+ 2.4GHz, 3GB DDR2, 360GB HDD, DVDRW, Vista Home Premium
^ the computer i have

550W Chiefmax (PSCH550) 20+4 Pin w/SATA ATX Power Supply P4 and AMD Compatible Model: PSCH550
^ the PSU i want because i want to upgrade to a bigger graphics card

1. Will it work?
2. Will it be impossible to hard to put in. Im fairly farmilar with the inside of a computer and i see how the diffrent plugs into things such as my motherboard cd drive hard drive ect.
3. Do you think i should go for a better power source that is under 50$ or so?

Also my current graphics card is a nivida GF210


I am running only 250w at the moment on my current power source and the graphics card says 300w min. I have been using this one for about 8 months or so. I play alot of World of Warcraft and im running around 40 fps at 1152x864 resolution.

Also I am thinking about getting a new monitor any suggestions =P and can a bigger monitor with hdmi or somthing make my computer/games run slower?

thank you so much for the people that go out of their way to help me with stuff like this

It should be ok. I would find out what motherboard you are using. GPUz; its a free download. You can then see what you need to plug in after findina pic of it.

That PSU not be a great buy if you have not got it already. Rick on Amazon states "well let me say it this way mine went bad shortly after i got it but was so cheap i didnt even try to warranty it lol but went for the xion 1058watt psu instead to replace it after the failure".

If you can say what card you are after and a budget we can help find a PSU!