What Computer is better and by how much ( a little, alot)?

This is my old computer http://www.cnet.com/products/dell-optiplex-gx280/specs/

This is the computer i'm getting
http://ironsidecomputers.com/index.php?main_page=product_info&cPath=28223_28241&products_id=344

How much better is the ironside. And don't tell me they both suck bc i know. My old computer broke, and the new one is easily upgradable. Can the new one run cs-go or gmod at high settings? And can it run rust on low? Ironside does good quality in the build, and a new netbook beats your old computer, but gt 730 pentium g4400 is disappointing at $500.
$440 Lenovo has upgrade capability issues but beats performance of the Ironside by a lot
http://www.newegg.com/...6883798505
gtx 745 / i3-4170
$500 is a bad price point for a new Desktop PC that you are not building yourself.
$500 Laptop can be compared to the Ironside desktop
http://www.newegg.com/...6834315131

There are open box PCs at Newegg with risk on their functionality that are far better where new ones should be $600+.

Since GMOD is low requirements, will look at CS: GO
By
http://www.notebookcheck.net/...849.0.html
http://www.videocardbenchmark.net/gpu_list.php
http://www.game-debate.com/...ce-gt-730m

The laptop is 26% stronger graphics processing than the Ironside desktop
GT 730 is 924 score at Videocard benchmark and GT 940M shows comparable, though laptops outperform at actual gaming on the same lab benchmark.
Laptop recorded 68.1fps average on ultra on CS: GO
They don't test GT 730 typically.
Expect that it comes close as cpus i5-5200U and G4400 are about comparable.

Your two older games should play well, but don't expect new gaming without upgrades.
The Lenovo $440 slim PC that is difficult to upgrade
CPU is 40% stronger and GTX 745 is over double the graphics performance.
There was an X51 Alienware with i3 and GTX 745 and people warned against it for low performance, and the Ironside is half the gaming performance.

Maybe, buy the $400 Ironside and add in a GTX 750 TI and hope the power supply included is not a piece of junk. You would need a GTX 750 TI with no 6-pin PCIe connection needed
https://pcpartpicker.com/parts/video-card/#c=164&sort=a8&page=1

$400 Asus
http://www.newegg.com/...6883221132
matches the GT 730 with R7 240 and the 8 core AMD CPU is great outside of gaming but still beats a G4400 in gaming.

a 6th gen i5 Lenovo needs a new power supply, system fan, and graphics card and is under $440
http://www.newegg.com/...6883798810
or i3-6100 8gb ram and 1tb hdd
http://www.newegg.com/...6883798803

So, your Ironside PC should do OK on GMOD and CSGO, but if you wanted anything newer than those games, you end up needing a new CPU, graphics card, and power supply most likely.

You are at a price point that you can't buy a good gaming PC complete.
You can upgrade lower end systems, take customer returns, or build your own.
Rust also has low minimums so it plays OK.

If you get past 2013 games, your system is really disappointing, and so close to getting something great. If you are not committed to it, think about the system. You're comparing your old single core on a ancient dead socket to a newer current dual core
There's at least 6 years between the 2

You're comparing your old single core on a ancient dead socket to a newer current dual core
There's at least 6 years between the 2