For $700 you can get way better than a Pentium D 820. I'd recommend a Conroe build or an AM2 AMD build.

You're better off financially if you go with an AMD build (not by much, but saving money is always nice), if you don't mind buying used, you can pick up a 3800X2 and S939 motherboard for under $200. But if you want to order from a place like Newegg, then you'd probably have to go and find an AM2 3800X2 from Newegg for 130 and an ASUS NF5 board for around 95 bucks. DDR2 ram is gonna cost you 170+ regardless, Newegg has 2gbs of G.Skill DDR2 for 175.

If you do want to go for Conroe, an E6300 will run you 183, a Gigabyte DS3 will run you 135, and ram will be 175. About 100 more than the AMD build, and definitely worth the extra money, but you only get $200 from that $700 budget to spend on a good video card.

With the AMD build $300 will score you a nicer video card, which is usually the biggest factor when it comes to gaming. But the Intel build nets you a faster running system for non-gaming, but leaves you room for a decent gaming card.

Go for AMD if you're really strapped for cash, they overclock pretty good, but Conroe also overclocks pretty damn good. Intel's E6300, when overclocked (which is incredibly easy BTW) can mop the floor with AMD's FX-62.

Y is the 805 better than the 820?  820 has a better FSB (533 - 800) and processor speed (2.66 to 2.8).  Isn't the 820 better?  I still don't understand how that works if it's true....*noob in training*

The 805 is a crapshoot, tom's hardware paired their 805 with expensive cooling, an expensive motherboard, and expensive RAM. Even if you do manage to get a good clocker that gets up to 3.8ghz, you'll have a space heater for a computer and end up spending a shitload on other components.

To make it short and simple, to make the 805 worth it, you spend as much as you would if you got a Conroe system (which I might add, people are getting 3ghz+ as a typical overclock with an E6300)

what buying the cpu at $90 and a 50 3rd party cooler is as much as a conroe cpu, buzzsaw you might want to check you figures again. And you need to get the 805 2.6 smithsfield cpu to oc with, i dont think any other ones oc that high except for the smithsfield and it has to be the 2.6ghz cpu. go to the tomshardware and read it. Or go to  newegg.com and look up the 805 smithsfield and read the reviews there, they will back up what i say. But if you want to go conroe go for it.

If you can afford it go with conroe hands down low energy use and more work per mhz. But if you cant go for 805 get a 3rd party cooler on newegg and oc to like 3.8 and have fun. I got my 3ghz th cpu to 3.8ghz on another motherboard and it was dman fast.