I have had the PC I ordered from Arbico about a year now.
I upgraded a few parts, including the case, CPU cooler and PSU. I also added a samsung SSD.
Here are my experiences...
I contacted the customer support about the upgrades and they where very useful and replied very fast. They where happy with all the upgrades and they said they wouldn't void the warranty apart from the case - this was understandable as a new case is pretty much a whole rebuild of the PC. As I was changing the case, I realised the CPU cooler's push bracket, was facing up... Now I thought they where meant to face down? I was taking it off anyway so it didn't bother me, the PC worked fine after all the upgrades. I have an AMD FX 8350 coming in the post and for my motherboard to support that chip, the bios had to be the latest version. Unfortunately, the bios was on a very late outdated version. (It was the earliest version that supports the FX 6100). So I had to go to the effort of flashing the bios myself.
Overall Arbico are a great company, and these minor issues shouldn't put you off buying at all but it's just something to point out :)