Budget PC for the in-laws, $450-$550

PCPartPicker part list / Price breakdown by merchant / Benchmarks

CPU: Intel Pentium G850 2.9GHz Dual-Core Processor ($69.99 @ Newegg)
Motherboard: ASRock B75M-DGS Micro ATX LGA1155 Motherboard ($61.97 @ Newegg)
Memory: Pareema 8GB (2 x 4GB) DDR3-1333 Memory ($31.89 @ Newegg)
Storage: Samsung Spinpoint F3 500GB 3.5" 7200RPM Internal Hard Drive
Case: Cooler Master Elite 431 Plus (Black) ATX Mid Tower Case ($34.99 @ Newegg)
Power Supply: Corsair Builder 430W 80 PLUS Certified ATX12V Power Supply ($34.99 @ Newegg)
Optical Drive: Lite-On iHAS124-04 DVD/CD Writer ($15.99 @ Newegg)
Operating System: Microsoft Windows 7 Home Premium SP1 (64-bit) ($99.99 @ Newegg)
Total: $349.81
(Prices include shipping, taxes, and discounts when available.)

Feel free to add an SSD for the the boot up drive and this will last a long time  

http://pcpartpicker.com/p/lyKJ This is the cheapest i can find for you. its as low as you should go. I got the i3 as it offers much much better performance then the pentiums and is newer

$415.94........... neweggs site is screwed up and item avail. is low.... maybe it's getting hacked ?..... but these items are good and will work together.

case
http://www.newegg.com/Product/Product.aspx?Item=N82E168...
PS
http://www.newegg.com/Product/Product.aspx?Item=N82E168...
ram
http://www.newegg.com/Product/Product.aspx?Item=N82E168...
opsys
http://www.newegg.com/Product/Product.aspx?Item=N82E168...
mobo/proc combo
http://www.newegg.com/Product/ComboDealDetails.aspx?Ite...

or you can buy this machine.

PCPartPicker part list / Price breakdown by merchant / Benchmarks

CPU: AMD FX-8320 3.5GHz 8-Core Processor ($179.99 @ Newegg)
Motherboard: MSI 970A-G46 ATX AM3+ Motherboard ($69.99 @ Amazon)
Memory: Patriot Viper 3 8GB (2 x 4GB) DDR3-1600 Memory ($25.99 @ Newegg)
Storage: OCZ Vertex 4 128GB 2.5" Solid State Disk ($99.99 @ Newegg)
Case: NZXT Gamma Classic (Black) ATX Mid Tower Case ($36.08 @ Amazon)
Power Supply: Corsair Builder 430W 80 PLUS Certified ATX12V Power Supply ($34.99 @ Newegg)
Optical Drive: Lite-On iHAS124-04 DVD/CD Writer ($15.99 @ Newegg)
Operating System: Microsoft Windows 8 (OEM) (64-bit) ($99.99 @ Mac Mall)
Total: $563.01
(Prices include shipping, taxes, and discounts when available.)

Which will just blow them away with its speed.BUT it will consume quite a bit more power than the Core i3 based system.About 80 watts at load and 15 at idle.

I wouldn't go beyond a Pentium.

Pentium G2120 (dual core) - $95
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

ASRock B75M-DGS MicroATX mobo- $55
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

G.Skill ECO Series 2x2GB DDR3-1600 RAM Kit -$40
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

SAMSUNG 830 Series 128GB SSD - $109
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

PC Power and Cooling Silencer MK III 400W Modular PSU - $70 ($50 with MIR)
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

Fractal Design Arc Midi case- $70
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

ASUS DRW-24B1ST/BLK/B/AS Black SATA 24X DVD Burner - $20
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

Cost without the OS: $459 (and no MIR)

Cost with Win 7 HP SP 1 @ $100: $559 (and no MIR)
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

Alternatives:
SeaSonic SS-300ET Bronze 300W PSU -$40
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

COOLER MASTER Silencio 450 - $70
http://www.newegg.com/Product/Product.aspx?Item=N82E168...


Notes:
1. You won't need the 400W PSU from a power point of view. It's just modular. If you don't care about that, go for the SeaSonic.

2. The Silencio 450 throws in a SD card reader as well, if that's important. But otherwise, the Fractal case seems to be better (from the newegg reviews). Could have gone cheaper on the case, i just wanted to throw in USB 3.0, and a case that looked non-gamer.

3. Don't know if you'll find a better deal on the OS, or if you want Win 8 for some reason. But for win 7, stick to Home Premium.

4. The mobo only has one on-board fan header, but the Fractal case has a fan controller, apparently. You can obviously hook the fans to molex connectors directly.

5. You may want to look at the -T model pentiums as well, like the G2100T (not available on newegg) or the older G860T/G645T/G640T/G630T/G620T without a major hit in performance, though the idle power consumption should be very similar, and this system will hardly ever be at full load. But i still think the G2120 is a better idea, fastest Pentium there is, and more efficient than the 65w G870.

6. You could shave a few bucks off on the RAM by using regular 1.5v sticks.

Finally what i tried to do with the build was:
1. Lowest power consumption without sacrificing too much performance.
2. Fast boot and application loading, along with reliability (Samsung's SSD)
3. Good silent cooling
4. Maximum usability from things like USB 3.0.
5. Trimming unnecessary features like 4 RAM slots
6. A clean build (modular PSU).

Cheers  

@Kamen_BG: Understating the power consumption a bit too much? 15w total system power consumption at idle would be difficult even for 35w CPU-based system, i should think...

If i look at tom's recent review of piledriver, then i see an idle power consumption of 92w for the FX-8350. If i subtract 50w for the GPU, etc that would be extra in their rig, i still think it'll be reasonable to expect a minimum of around 40w.

They'll never need anything more than this:

PCPartPicker part list / Price breakdown by merchant / Benchmarks

CPU: Intel Pentium G850 2.9GHz Dual-Core Processor ($64.99 @ NCIX US)
Motherboard: ECS H61H2-M12 Micro ATX LGA1155 Motherboard ($29.99 @ Newegg)
Memory: Samsung 4GB (1 x 4GB) DDR3-1600 Memory ($16.99 @ Amazon)
Storage: Western Digital Caviar Blue 160GB 3.5" 7200RPM Internal Hard Drive ($39.99 @ Microcenter)
Storage: Plextor M5S Series 64GB 2.5" Solid State Disk ($64.99 @ Newegg)
Case: Rosewill FBM-02 MicroATX Mini Tower Case ($24.99 @ Newegg)
Power Supply: Rosewill 350W ATX Power Supply ($26.99 @ Amazon)
Optical Drive: Lite-On iHAS124-04 DVD/CD Writer ($15.99 @ Newegg)
Total: $284.92
(Prices include shipping, taxes, and discounts when available.)

they may not need a lot of storage but windows will grab what it can with hibernate, swap file, search . .ect. granted some of this can get turned off. bottom line is for this budget getting an SSD is a complete waste.

will it send emails faster? no.
will it load pages faster in FF or chrome? no. (maybe in the cache but 0.0045 seconds   )
will it print faster? no.
will it process a word document faster? no.

whoopee it can boot windows faster, let they keep rebooting the computer to enjoy that enhancement.



that is a great build but either add a small hard drive for the USER files to save space or just drop the SSD entirely.