Although Minecraft and most Steam games do not take much graphics performance, both of those PCs are bad at gaming for their price, and use low quality parts in general.
The gaming is based mostly on the graphics card, and the $700 Dell shows only a GT 720 and you get to $800 adding a GT 730 to the HP. Those are crazy prices.
http://www.newegg.com/...erSearch=1
CyberpowerPC Desktop PC Gamer Xtreme H170 would be great at $765 but has reviews showing a faulty graphics card in some of them.
The $630 one iBUYPOWER Desktop PC ARC SERIES NE781K Intel Core i5 4690K (3.50GHz) 8GB DDR3 1TB HDD 120GB SSD Windows 8.1 64-Bit AMD Radeon R7 250X 1 GB
where you buy a $20 or less wireless card or dongle if you need it,
An R7 250X is a little better than GTX 745
http://www.game-debate.com/...on-r7-250x
An Envy is about $900 at these specifications.
CPU benchmark
https://www.cpubenchmark.net/...u_list.php
graphics card benchmarks
http://www.videocardbenchmark.net/gpu_list.php
R7 250X capability
http://www.anandtech.com/bench/product/1126