To be fair, I would like to show you what $1000 gets you for a new PC if you build it yourself.
Also, I couldn't click any of the links, it looks like they weren't formatted properly. When I searched for the PC's you are looking at, I found they were sold at an Australian retailer. I will assume, for now, that you are in AU and need AU pricing. If your budget is $1000 USD, please let me know :)
PCPartPicker part list / Price breakdown by merchant
| Type | Item | Price |
|---|---|---|
| CPU | Intel Core i5-4460 3.2GHz Quad-Core Processor | $250.00 @ Umart |
| Motherboard | Asus H81M-E Micro ATX LGA1150 Motherboard | $69.00 @ Centre Com |
| Memory | G.Skill Ripjaws Series 8GB (2 x 4GB) DDR3-1600 Memory | $90.00 @ IJK |
| Storage | Western Digital Caviar Blue 1TB 3.5" 7200RPM Internal Hard Drive | $72.00 @ Centre Com |
| Video Card | MSI Radeon R9 280X 3GB TWIN FROZR Video Card | $325.00 @ Umart |
| Case | BitFenix Comrade ATX Mid Tower Case | $59.00 @ PCCaseGear |
| Power Supply | Silverstone Strider Essential 700W 80+ Bronze Certified ATX Power Supply | $89.00 @ Umart |
| Prices include shipping, taxes, rebates, and discounts | ||
| Total | $954.00 | |
| Generated by PCPartPicker 2015-04-06 20:09 EST+1000 |
This is about the best bang-for-the-buck I could fit under $1000 (AUD). It has a MUCH better processor than the units you were looking at.
To put this in perspective, this PC costs ~$950 and includes an R9 280X GPU. The $950 option from the website I believe you were referencing comes with a lower end AMD Athlon 860K CPU and an Nvidia GTX 750. The case is also MUCH nicer and easier to build in/upgrade if you ever want to.
Link to CPU comparison between 860K and i5-4460
Link to GPU comparison between GTX750 and R9 280X
I think the benchmark information speaks for itself, mostly. The Pre-built PC will barely last a couple of years and already can barely handle medium settings in games, while the DIY build will currently run high-ultra settings and will not need replacement/upgrade for a MUCH longer time. If you have any questions please ask. I can provide detailed build instructions and more product information if you are unsure. :)
Have fun! ☻