First time building a computer

Hi. I'm currently on a quest to build my first computer, and was hoping for a little insight as far as my choice in parts.

APPROXIMATE PURCHASE DATE: As soon as possible. Hopefully tonight. BUDGET RANGE: $700 or so. A little over's not the end of the world, but I'd like to keep it under if possible.

SYSTEM USAGE FROM MOST TO LEAST IMPORTANT: Gaming, Multitasking, Internet Browsing

PARTS NOT REQUIRED: Keyboard, Mouse, Monitor, Speakers, or DVD Drive

PREFERRED WEBSITE(S) FOR PARTS: Newegg.com

PARTS PREFERENCES: None, really

OVERCLOCKING: Maybe SLI OR CROSSFIRE: Maybe

MONITOR RESOLUTION: 1920 * 1080, but I think I'm going to get a second monitor eventually.

ADDITIONAL COMMENTS: I don't think so.

Here's what I'm looking at right now:

Processor/Motherboard - $314.99

http://www.newegg.com/Product/Comb [...] mbo.200064

AMD Phenom II X4 955 Black Edition Deneb 3.2GHz Socket AM3 125W Quad-Core Processor Model HDZ955FBGIBOX - Retail

BIOSTAR TFORCE TA790GX 128M AM3/AM2+/AM2 AMD 790GX HDMI ATX AMD Motherboard - Retail

Graphics Card $94.99

http://www.newegg.com/Product/Prod [...] 6814102770

SAPPHIRE 100245L Radeon HD 4850 512MB 256-bit GDDR3 PCI Express 2.0 x16 HDCP Ready CrossFire Supported Video Card - Retail

I'm planning on eventually buying a second one of these to Crossfire, probably whenever I get a second monitor, but money's a little tight so I think I'm going to hold off. Do I need to do anything in order to add the second graphics card, or will it be recognized as soon as I add it? Also, do I need anything to link the 2 cards?

Hard Drive - $99.99

http://www.newegg.com/Product/Prod [...] 6822136284

RAM - $44.99

http://www.newegg.com/Product/Prod [...] 6820231166

Case / Power Supply - $129.98

http://www.newegg.com/Product/Comb [...] mbo.201850

I honestly have no idea what I'm looking for as far as power supply or case, so any help there would be appreciated.

As far as overclocking goes, is that something I'm able to do with stock cooling? I know I won't get great speeds, but I'd like to bump it up a little bit. Does that motherboard work well for it? Also, is there anything I'm forgetting? I've heard competing opinions on thermal glue. Is it worth it? If so, what should I get? Also, my last thing is that I have an MSI 6600GT lying around that I could use temporarily as a graphics card. Would it be beneficial to use that for a while and hold off until prices go down, or should I just take the plunge?

Thank you all for your help, and I'm sorry I asked a lot of questions.

Thanks. I think I'm going to go with the EA650. What sort of difference would I see if I went for the other one?

The modular PSU would mean less clutter in the case and slightly better air flow because of it.