OPSDanni

You can't custom make components. You can only custom a build through asking for components. e.g I want a low voltage I3 2120, gigabyte H61M-S2PV, WD RD HDD, Kingston RAM. All manufactures that say they build custom can do this, unlike HP who use only seagate HDD's for example.

I would personally recommend going for a branded machine. HP are in the fortune 500 top 10 so are a pretty save bet and although I'm not a massive fan Dell are up high as well. Both offer a 5yr warranty and depending on how many you are after can do custom machines to the level you'll need. Unless they are being used for massive graphical work