First of all , the first PC is too cheap and the parts of it won't last for long (even now they are sucky , Athlon is a very old tech similiar to Pentium , they are like 10 y.o.)
The second one is a better choice , it's parts will last for long and you won't even need to upgrade it for long long time.
But the GPU you picked sucks , it's from last year plus it's a cheap model (ending with 50 = cheap , ending with 70 = medium , ending with 90 = ultra)
Crossfire is only gonna help you on games , and these GPUs ain't anything special or good to buy two of them , better get one strong than 2 weak
example
http://www.plaisio.gr/Computers/Hardware/SVGA/Sapphire-6970-PCI-Express-GDDR5-2GB-21187-00-40R.htm
Simply superior , it's one it's strong and you gonna spent 60 euro less
Mobo looks fine
Ram looks fine
CPU is fine
But don't forget , HDD plays a vital part then we talk about performance. SSD = Pure win but they cost quite much and they are small then we are talking about GBs , it depends on your pocket if you ask me.
About your last sentence , dud even if you have 9.99 Ghz cpu with 32GB DDR4 and you got a sucky prehistoric GPU it will still lag , all the hardware must be balanced in order to have a healthy PC , with the meaning of everything going smoothly