New graphics card questions

[Edonnel]

I know I have made a topic about my graphics card problems before, but I feel that these questions are necessary for the sake of my computer (and my personal health ). Before I ask, I want to say that I know my computer is old (I DON'T need to be reminded), my new card isn't the best (at all), and I'm not a super computer gamer, so I don't need super performance nor do I play GRAPHIC INTENSIVE GAMES, but I don't enjoy headaches, either. I just want a decent graphics performance.

Specs:
Computer- Dell Dimension 4550, Pentium 4 CPU 2.53 GHz, 1.00 GB of RAM, Single-processor (stop laughing)
OLD Graphics Card- NVIDIA Geforce4 MX 64 MB AGP (now you see why I need the upgrade)
NEW Graphics Card (not in comp. yet)- ATI Radeon HD 3450 512 MB APG (not the best, but DEFINITELY an upgrade)

QUESTION TIME:
1.) My current crap card does not require a power cord, but the new one DOES, so what am I looking for? (I think it needs a "four-pin molex")
2.) My current power supply will definitely not do (250w). The card requires at least 300w. How much power do I need overall? I'm thinking 550w, but I don't want to run on a wild guess.
3.) What's the best way to install this thing? I mean, the old card is NVIDIA and the new one is Radeon. Do I uninstall the NVIDIA drivers, shut down, put in new one, then do I start in safe mode and use the CD to install the driver? Or do I start in normal mode and hope it installs itself?

Remember! My computer is older, so the card slot is AGP! I think that's all my questions and I hope you've read through all of this. If I have any more, I'll be sure to post it! Thank you for reading and please help me!

EDIT: Can I buy just any ATX power supply (with enough wattage)? I was browsing online and they all looked the same size and could fit in my computer. I'm thinking I should buy the cheapest one off amazon because a different site I was on, had me put in my computer specs and told me a 450w would cost $80! I don't want to pay that much!

[TherealYeno]

You will probably only need something in the 400W range. All the connectors you need will be on the PSU so you don't need to worry about that, just plug them into the matching slots. For the drivers I think the best way is to do it like you said. Uninstall the nvidia drivers and restart. Don't install the drivers from the CD have the newest ones already downloaded from the AMD website and install them once you turn the computer on with the AMD card.

Here is a good quality reasonably priced PSU. http://www.newegg.ca/Product/Product.as ... 6817371029

[UNPAIDBABYSITTER]

You need to upgrade your CPU or it will be a huge bottleneck for any GPU

I will Say get a C2D and 450W PSU

[Edonnel]

Thanks guys! Took long enough though... . Anyway, I found a 400w power supply. Will that be enough? I'm pretty sure it will because the video card requires a POWER SUPPLY of 300w or higher, not USES 300w (Am I right?) Also, thank you so much for clearing up the installation, It's been a pain to ask people and they say "Uninstall, take it out, put new in, startup". Thanks again!

I'll be sure repost in a week or two when my PSU arrives!

EDIT:Also, just for giggles, what kind of CPU upgrades would work for my above specs if I ever wanted to upgrade that? Price estimate? Link maybe? Thanks!

[Edonnel]

Okay guys! I got all my stuff working and I'm happy! I had to cut a hole in the back casing with a dremel since the PSU was a bit different than the stock one, but it was well worth it. I'm also glad I didn't get a more expensive card since my bios can only use half a gig of video memory :/ . Thanks for everyone's help!