Noob looking for advice on upgrade

I'm not sure if this is where this goes cause I'm kind of building a new PC, but I'm also not. I'll try to explain what I want to do as best I can.

My current computer is rather old (5 years I think), was not made to be a gaming PC, and is struggling to run newer games at decent framerates even at low settings. I don't have enough money right now to get a completely new computer, so I'm going to buy whatever I can now, and use parts from this computer to fill in for the peices I can't afford quite yet. I would like to get a new MoBo that is ready for upgrades as they come, which will mean I need a new processor and RAM.

The parts I think I MAY be able to use from my old computer are the case, PSU, CPU cooler, and CD drive. The parts I KNOW will be compatible are the HDD and GFX card. I'll put the specs for my current pc at the bottom.

I hope that makes sense. Here's the outline thing:


Approximate Purchase Date: Within 2 weeks


Budget Range: 260$


System Usage from Most to Least Important: Gaming, HD video watching, video chat and voice chat, general internet usage.


Are you buying a monitor: No


Parts to Upgrade: Mobo, CPU, RAM - these parts I definitely need.


Do you need to buy OS: No


Preferred Website(s) for Parts: I'll use any site that is not shady.


Location: Athens, Georgia


Parts Preferences: Parts with good linux compatibility.


Overclocking: Yes


SLI or Crossfire: No


Your Monitor Resolution: 1680x1050


Additional Comments: I use windows for gaming and Linux for most other things, but with Steam for Linux coming up I'll be using linux for gaming soon as well.


And Most Importantly, Why Are You Upgrading: Explained at top.



Ok here's the specs of my current PC:

It's a Dell Dimension e520

Processor: Intel Core 2 Duo E6320 @ 1.86GHz
RAM: Crucial 8GB (4x2GB) DDR2
Motherboard: Dell Inc. 0WG864 w/ Intel P965/G965 chipset
GFX card: AMD Radeon HD 6670 (XFX Pine Group)
HDD: 250GB Seagate ST3250820AS (RAID)
Optical Drive: PBDS CDRWDVD DH-48C2S

The case is weird so I don't know if it will fit a newer mobo, and the cpu fan is in a housing so I'm not sure that will work for the new system either.

Any advice is much appreciated.