Request help with upgrade (if possible) or build

[jrs20]

My 7-year old desktop is in need of an upgrade or replacement, and I was hoping someone here could help me figure out if I can upgrade it or, if not (or if it's not worth it), recommend a build. The current desktop gives me tolerable performance for WoW PVE (I don't PvP), but since I've decided to give Wildstar a try, I'll at least need more memory than I currently have.

What I have:
Intel® Core™ 2 Duo E6850 3.0GHz 4MB Cache 1333MHz FSB
800MHz DDR2 SDRAM - 4GB - 4 x 1024MB
NVIDIA nForce 680i SLI Motherboard
768MB NVIDIA® GeForce™ 8800 GTX
250GB Serial ATA 3Gb/s 7,200 RPM w/ 8MB Cache
Killer K1 Gaming Network Interface Card
700 Watt Power Supply

How do I tell if I can install additional memory in the computer I have? Do I have to open it up to check? Is it even worth it to upgrade the system? Or should I just re-invest in a new one?

If I do need a new one, here's what I'm looking at:
Budget: Probably $800-$900. (I could be convinced to go higher, but I think that's probably enough for what I use it for and how often I play, based on some of the other forum threads I've read recently)
WoW and Wildstar on high settings (Ultra not required)
Any other intensive software or special things you do: None
Country: USA
Parts that can be reused: See above
Do you need an OS?: Yeah. No real preference between the various Windows
Do you need peripherals (e.g. monitor, mouse, keyboard, speakers, etc)? No

I've seen a couple of the other recent threads that had some recommendations for $750-$800 price range. No need to retype those here, but I would be interested in hearing if anyone would recommend something different from those recommendations.

Thanks in advance for any assistance.

[Deleted]

That pc you got is quiet old and any money on it would be wasted. It doesnt even have ddr3 and you probably have a 32bit o/s that can only utilize up to 4GB of ram anyway.
Are you interested in having a unlocked cpu to overclock it? The benefit obviously is that in cpu heavy games like wow (mmo's) you will see an improved performance in fps during raiding.

- - - Updated - - -

Here's a build that you can't overclock. Assuming as you said you don't game all that much.
PCPartPicker part list / Price breakdown by merchant / Benchmarks

CPU: Intel Core i5-4690 3.5GHz Quad-Core Processor ($209.00 @ Amazon)
Motherboard: Gigabyte GA-H97-D3H ATX LGA1150 Motherboard ($99.99 @ Amazon)
Memory: Kingston Fury Black Series 8GB (2 x 4GB) DDR3-1600 Memory ($64.99 @ Amazon)
Storage: Crucial M500 120GB 2.5" Solid State Drive ($69.81 @ NCIX US)
Storage: Western Digital Caviar Blue 1TB 3.5" 7200RPM Internal Hard Drive ($55.99 @ NCIX US)
Video Card: Asus Radeon R9 270X 2GB DirectCU II Video Card ($189.99 @ NCIX US)
Case: Corsair 200R ATX Mid Tower Case ($49.99 @ Newegg)
Power Supply: EVGA 500W 80+ Bronze Certified ATX Power Supply ($34.99 @ NCIX US)
Operating System: Microsoft Windows 8.1 (OEM) (64-bit) ($89.98 @ OutletPC)
Total: $864.73
(Prices include shipping, taxes, and discounts when available.)
(Generated by PCPartPicker 2014-06-06 19:08 EDT-0400)


To save money to the above build you got 3 options:
-Drop the ssd completely.
-Downgrade from the R9 270X to R9 270 That saves you around 30-40bucks and you will loose 11% gpu performance.
-Go for an i3 4350 proccessor instead of the i5 and save 65$.

[jrs20]

Great, thanks for the help!