minimum worthwhile upgrade?

What is your budget?
What is your [desired] display resolution?
What version of Windows are you running?
What is the brand/model of your PSU? Does it have a 6-pin PCI-E power connector on it? 20-pin or 24-pin mobo power connector?

budget: likely no more than $300-$400
display resolution: 1024x768 or 1280x1024 (that's my usual minimum, and the max my monitor will do, respectively)
windows: XP Pro (sorry; forgot that wasn't necessarily obvious with my hardware age)
power supply: Antec NEO somethingorother... 480W i think. would have to get home and check for the PCIE connection; It'll do either a 20 or 24 pin mainboard connection

Ok. The PSU should be adequate. With that budget, I think I can come up with a decent AM2 parts list. I'll post back shortly.

For that much money, you can easily buy a new mobo, CPU, RAM, and a GPU. I mean, I just picked up an E2200 and an Asus P5LD2 for around $200 (love the mobo for it has 3 PATA ports). You're looking at about $50 for 2GB of decent RAM. That would leave you $150 for a new GPU.

Here's a quick list. Explanations are at the bottom. There are some obvious compromises, but I didn't bust your stated budget.

BIOSTAR TF560 A2+ AM2+/AM2 NVIDIA nForce 560 MCP ATX AMD Motherboard - Retail
Model #: TF560 A2+
Item #: N82E16813138081
$79.99 $79.99

SAPPHIRE 100208L Radeon HD 2600XT 256MB 128-bit GDDR3 PCI Express x16 HDCP Ready CrossFire Supported Video Card - Retail
Model #: 100208L
Item #: N82E16814102700
$92.99 $92.99

AMD Athlon 64 X2 4000+ Brisbane 2.1GHz Socket AM2 65W Dual-Core Processor Model ADO4000DDBOX - Retail
Model #: ADO4000DDBOX
Item #: N82E16819103774
$59.99 $59.99

A-DATA 2GB (2 x 1GB) 240-Pin DDR2 SDRAM DDR2 800 (PC2 6400) Dual Channel Kit Desktop Memory Model ADQVE1A16K - Retail
Model #: ADQVE1A16K
Item #: N82E16820211066
$45.99 $45.99

Seagate Barracuda 7200.10 ST3250310AS 250GB 7200 RPM SATA 3.0Gb/s Hard Drive - OEM
Model #: ST3250310AS
Item #: N82E16822148261
$66.99 $66.99

Subtotal: $345.95

Ok. The 2600XT is a weak for gaming, but a $199 HD3850 would have busted your budget. If you have wiggle room, here's where it should go.
The RAM is only 5-5-5-18 at stock, but again the focus was on cheap. I'm not sure how much real difference you'd see here. As a quick pick, I'm sure someone else can find better.
You'll need a new SATA hard drive, because most modern mobos support only a pair of IDE devices. A good option would be to build this system, then cycle through your existing IDE hard drives one at a time, copying what you need off of them onto the drive in this PC.
A 320GB drive isn't much more, but again I was trying to minimize the cost.
Good luck with your upgrade.

I mainly agree with jtt283, you can overclock those X2 processors a lot just on stock cooling. I would throw in artic silver 5 thermal paste, and I would recommend G.Skill for ram but many suggest Crucial for stability, I have G.Skill with no problems, plus they have a life time warranty.


4-4-4-12 @ 2.2 volts
Crucial Ballistix 2GB (2 x 1GB) 240-Pin DDR2 SDRAM DDR2 800 (PC2 6400)
http://www.newegg.com/Product/Product.aspx?Item=N82E168...
$74.99 - Rebate (If you qualify) + Free shipping

The RAM I use and would suggest but some people have had it die on them, but I have not had this occur to me.

4-4-3-5 @ 2.0-2.1 volts
G.SKILL 2GB (2 x 1GB) 240-Pin DDR2 SDRAM DDR2 800 (PC2 6400)
http://www.newegg.com/Product/Product.aspx?Item=N82E168...
Price: $69.99 + Shipping