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I think I would rather have 4TB HDD and 128 SSD and 16GB

I recommend building your own and getting exactly what you want, if you feel up to it. If you want similar/better performance to a 15" rmbp, get an i5 or i7 4xxx processor and a midrange graphics card like the Nvidia 750 or 660. Also, don't skimp on the motherboard, as a cheap one can be a headache. Try to get one that has good reviews and is the recommended size for the case.

Will probably cost ~$1000-1200
 
Intel Core i7-4770 Haswell 3.4GHz LGA 1150 - $299.99
ASUS MAXIMUS VII HERO LGA 1150 Motherboard - $219.99
G.SKILL Ripjaws Series 8GB (2 x 4GB) 240-Pin DDR3 SDRAM DDR3 1600 - $79.99
SAMSUNG 840 Pro Series MZ-7PD256BW 2.5" 256GB SATA III SSD - $199.99
EVGA SuperClocked 02G-P4-2662-KR GeForce GTX 660 2GB - $219.99
Corsair Carbide Series 200R ATX Mid Tower Case - $59.99
Thermaltake ToughPower Grand TPG-0650M - PSU - $109.99
LG Black Blu-ray Burner SATA WH16NS40 - OEM - $64.99
Dell U3014 Black 30" LED Backlight LED Monitor (2560 x 1600),IPS panel - $1199.88
Microsoft Windows 8 Professional 64-bit (Full Version) - OEM - $139.99

Price: $2594.79

Keep in mind that you'd still need a mouse, keyboard, and at least 1-2 additional fans inside the case for cooling, plus any other items you might want in the machine. While you could go with a cheaper monitor, you would sacrifice either screen size, resolution, or brand reliability in the process. I included the Blu-Ray burner because you pretty much have to have an optical drive to do anything in Windows, since most Windows software still comes on discs unless you use services like Battle.net, Steam, or Origin for games. There is no true equivalent on the processor side, as the mobile parts have different clock rates, TDPs and even form factors from their desktop counterparts.

Why would you use newegg when you have pcpart picker?

http://pcpartpicker.com/p/QpZtQ7

PCPartPicker part list: http://pcpartpicker.com/p/QpZtQ7
Price breakdown by merchant: http://pcpartpicker.com/p/QpZtQ7/by_merchant/
Benchmarks: http://pcpartpicker.com/p/QpZtQ7/benchmarks/

CPU: Intel Core i7-4770 3.4GHz Quad-Core Processor ($299.98 @ OutletPC)
Motherboard: ASRock H87 Performance ATX LGA1150 Motherboard ($119.99 @ SuperBiiz)
Memory: G.Skill Ripjaws X Series 8GB (2 x 4GB) DDR3-1600 Memory ($72.00 @ Newegg)
Storage: Samsung 840 EVO 250GB 2.5" Solid State Drive ($139.00 @ Amazon)
Storage: Western Digital Caviar Black 1TB 3.5" 7200RPM Internal Hard Drive ($88.97 @ OutletPC)
Video Card: EVGA GeForce GTX 760 2GB Video Card ($239.99 @ NCIX US)
Case: Corsair Carbide Series 300R Windowed ATX Mid Tower Case ($79.99 @ Amazon)
Power Supply: Corsair CSM 450W 80+ Gold Certified Semi-Modular ATX Power Supply ($59.99 @ Amazon)
Optical Drive: LG GH24NSB0 DVD/CD Writer ($14.99 @ Newegg)
Operating System: Microsoft Windows 8.1 (OEM) (64-bit) ($89.98 @ OutletPC)
Monitor: Asus PB278Q 27.0" Monitor ($466.60 @ Amazon)
Total: $1671.48
(Prices include shipping, taxes, and discounts when available.)
(Generated by PCPartPicker 2014-06-01 13:11 EDT-0400)

Macs are nice but please don't try to spin this into something else.

(Yes my selections may not be the best but they give a pretty good idea).

You are getting significantly more CPU power (full turbo), much more GPU power, more storage, and a nice large usable monitor (a 27" 1440p is just as useful if not more as 15.4" 1880p due to the much larger amount of real estate). I've shaved over $900 off the previous build.

You would need a mouse and keyboard/speakers but those can be used for multiple builds and if you had a previous desktop you could use those (alternatively the monitor, case, ODD, HDD and SSD can be resused making subsequent builds even cheaper).

Apple provides nice computers and has OSX but from a pure value perspective rmbp can't compare.
 
What about this one, it is $550 and has i5. http://www.pcworld.com/product/pg/1459148373/detail

About how much money can you save if you build your own PC instead of buying a brand like Dell?

For a budget PC, not much. Dell gets Windows 8 for around $20, where you pay $100 (minimum) for it. The trick is that when you want to get into a higher end computer, you can build a high end one for about 2/3 what Dell would charge. At $500, the dell you linked to is still middle to low end.
 
Okay, I'll answer your question.

Because I know and have used Newegg for years with no troubles, and I don't know this pcpartpicker thing. At all.

Then I strongly recommend it. Links parts to lowest retailer in the country and informs you of rebates and provides pricing over time. A high/mid end build will save $50+.
 
I know this suggestion isn't a desktop, but here's an idea.

We have a Toshiba Satellite P870 desktop replacement laptop with specs that are on par with, if not better than a fully configured MacBook Pro.

You get a 3rd generation quad core Intel Core i7 processor, a 1TB hard drive or SSD, 8GB of DDR3 RAM (Expandable to 32GB), dedicated NVIDIA GPU with 2GB of video memory and a decent 17.3" display. When we bought it it cost us $1,500 before taxes. It was on sale too.

http://www.goodgearguide.com.au/review/toshiba/satellite_p870_notebook/459978/specs/
 
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