Alright guys I need some advice on what to do with my computer.  Long story short I added a cheap graphics card to be able to play a couple games a little better and I wasn't really impressed.  So I decided to go bigger which of course required a power supply.  well of course the mother board that dell used in my inspiron is not compatible with aftermarket ATX power supplies even though it is an ATX board.  So should I just upgrade my mother board and processor and use it in the dell case or should I go ahead and get a barebones kit say from new egg or tiger direct?  Can I use my hard drive that's in my dell currently with a new mother board?  I believe it's currently SATA II.  I am currently running Windows 7 and I would like for it to stay that way and I don't want to lose anything I have on it.  My other option is to clone the drive to a new larger drive.  But with my motherboard in the dell being SATA II idk if it will recognize a new drive to clone it.  
Any advice please share as this is the first time I am thinking of doing a build of any kind on a computer
Here is the barebones kit I am looking at: 
http://www.tigerdirect.com/applicati...755&CatId=7718
Current motherboard specs: 
http://www.findlaptopdriver.com/specs-f896n-dell/
Here are my current system specs:
OS Name	Microsoft Windows 7 Home Premium
Version	6.1.7601 Service Pack 1 Build 7601
Other OS Description 	Not Available
OS Manufacturer	Microsoft Corporation
System Name	MIKE-PC
System Manufacturer	Dell Inc.
System Model	Inspiron 546
System Type	x64-based PC
Processor	AMD Phenom(tm) 9750 Quad-Core Processor, 2400 Mhz, 4 Core(s), 4 Logical Processor(s)
BIOS Version/Date	Dell Inc. A11, 1/19/2010
SMBIOS Version	2.5
Windows Directory	C:\Windows
System Directory	C:\Windows\system32
Boot Device	\Device\HarddiskVolume2
Locale	United States
Hardware Abstraction Layer	Version = "6.1.7601.17514"
User Name	Mike-PC\Mike
Time Zone	Eastern Daylight Time
Installed Physical Memory (RAM)	8.00 GB
Total Physical Memory	8.00 GB
Available Physical Memory	5.81 GB
Total Virtual Memory	16.0 GB
Available Virtual Memory	12.8 GB
Page File Space	8.00 GB
Page File	C:\pagefile.sys