New member has a few questions about first build

Hi I'm new here to this forum (and overclocking in general) and I am working on my first build. I've really had a tough time picking out part because I'm on a bit of a budget and besides that I always suffer from buyers remorse when I buy something and the next week I find a better part for around the same price. I probably shouldn't worry because anything I buil will be better than what I have: hp a1101n (specs Intel Celeron 2.93 GHz, 1.5 GB ram, and a radeon 2400hd). If I could get a few opinions and ideas on what I've already purchased and what else I should get for the most bang for my buck I would be greatly appreciated.

Here's what I have so far:
LG DVD/CD Burner
http://www.newegg.com/Product/Prod [...] k=gh22ns30
MSI P43 Neo3-F (PCB 1.0)
http://global.msi.com.tw/index.php [...] od_no=1728
A-DATA DDR2 800 240pin Unbuffered-DIMM Non-ECC Memory 2x2GB (4GB total)
http://www.adata.com.tw/en/product [...] No=AD2800U
Thermaltake SopranoRS 101
http://www.thermaltake.com/product [...] +101&ovid=

WD Caviar Blue 320 GB, 3 Gb/s, 16 MB Cache, 7200 RPM
http://www.wdc.com/en/products/pro [...] riveid=299

What I'm looking for:
A duo or quad for under $200. Looking for the best performance for multitasking and hd video. Will do some light overclocking but very stable ( don't want to risk screwing anything up because I wont have the money to replace it). I was looking at the E8500 or Q6600 but with prices dropping I'm flexable.

A good power supply. Not sure what wattage would be appropriate but Ihave heard Corsair is the best. Would rather not spend over $100. Modular would be a plus but I'm sure that's stretching it.

A good budget viedo card (is that an oxymoron?) below $100. I don't game much but would like to be able to play the latest games at 1680x1050. I was looking at the Radeon HD 4670. It's gotta be better than the 2400 right?

Not sure If I'm missing anything but if I am maybe you'll tell me. I don't need a monitor, KB or mouse, and I'm sure I can find an OS.
I know those were a lot of questions but any opinions on what I already have or need to get would be very appreciated. This forum looks very helpful and busy so I might stay awhile.

What budget are you trying to work with for the overall build?
HD 4670 isn't an especially great choice for gaming on a 1680x1050 res monitor.

Thanks for the wish list!

Like I said, these are the things I've alreadys purchased...
LG DVD/CD Burner
MSI P43 Neo3-F (PCB 1.0)
A-DATA DDR2 800 240pin Unbuffered-DIMM Non-ECC Memory 2x2GB (4GB total)
Thermaltake SopranoRS 101
WD Caviar Blue 320 GB, 3 Gb/s, 16 MB Cache, 7200 RPM

What's wrong with MSI? I've heard good things about that board.

Power supply - the choice from Levi is a very good one.
http://www.newegg.com/Product/Prod [...] 6817703015
For graphic card at $100 the HD4830
http://www.newegg.com/Product/Prod [...] 6814102803
personally i'd go with the E8500 rather then the Q6600, but there's lots of people that would disagree.
http://www.newegg.com/Product/Prod [...] 6819115036

The MSI P43 motherboard doesn't support crossfire, a quality 500w unit like the PC P&C will be fine.