First time builder with questions

[tehbriz]

Trying to put together a new gaming system on about a 1200-1300 budget. I'm reusing parts from my current pc for the build. I don't have to have top of the line, but i want to be able to play mainly MMORPGs on my 27 inch widescreen HD tv with a fairly high resolution.

Parts to buy:

Intel Core 2 Duo E6750 or 6850
eVGA 122-CK-NF67-A1 or 122-CK-NF68-A1
eVGA nvidia 8800 320mb KO
160 MB Maxtor HD
Sony 20X DVD R/RW drive
2 GB DDR-2 800MHz RAM
Vista Home Premium 64bit

Parts Recycled:

420W power supply
16X DVD R/RW drive
x-blade case
Sound Blaster Audigy ZS sound card (or something like that)
1 GB DDR-2 RAM

Now Questions...

Is there a significant performance difference between the 6750 and the 6850 processors and is it worth the extra $75 for a system that doesn't need to be the most powerful rig around?

Same question for the motherboard but with a $20 price diff. Or what suggestions do you have for a possibly better $200ish mboard? I don't need an SLi board, but i would like one incase i want to throw another card onto my rig in the future.

I'm planning on using my existing 1GB stick of ram in the new comp also, but i dunno if it runs at 800 MHz. I know from reading some stuff lately that i don't want to buy 800 mhz ram and mix it with a lower rate because all the memory will run at the lower speed. How can i find out what MHz rate my current stick is? Also, if it is an 800 MHz stick would it still be ok to run with 2 kit sticks that are a diff brand from my current?

Last question is overclocking. Should i do it, and is it safe? Will I need a bigger power supply? I have read that eVGA is great for overclocking (their mboards and GPUs). If i do overclock will i need to buy a better heatsink/fan for my processor?

Any additional comments or suggestions about the build you might have would be appreciated as much as answers to my questions already up.

Thanks

[tehbriz]

also. i'd like some help with my current pc. it randomly goes to a blue screen and starts making a reving sound a lot like when you give your car gas in neutral then let off then gas it again. when the problem first started i would get some message about my graphics card once i got the system back up. the message doesn't come anymore, but sometimes i'm taken to the black system screen where you can only use your keyboard and change system settings(dunno what it's called. sorry). the screen tells me i've had a fatal error and apparently wants me to change some settings although i'm not told what. i took the case apart and cleared a ****load of dust from my heatsink which has made the problem occur less oftem, but it still happens. nothing ever seems excessively hot after the crash. any ideas what the problem is?

[drummerboy92]

If you can, edit your first post instead of double posting. Thanks.

The e6850 doesn't have much performance over the e6750. Go with the e6750.

I would recommend this motherboard:
http://www.newegg.com/Product/Produc...82E16813131180
Sli is discouraged on this forum, because one new video card can beat two old ones. They also have versions of that motherboard with extra features for more $ if you look around.

I would recommend this Harddrive. good band for the buck:
http://www.newegg.com/Product/Produc...82E16822148140

You almost definetely won't be able to reuse that power supply with that 8800gts. Try this one:
http://www.newegg.com/Product/Produc...82E16817139002

In my opinion, overclocking isn't worth it. It takes a lot of time and work, and you risk a lot of expensive computer parts.

I wouldn't recommend mixing and matching new high performance and older RAM. 64 bit Vista uses 4 GB of RAM.