I get asked about a recommendation for a new PC a lot (obviously). These days its a lot easier than it used to be so here you go in one sentence, for a standard business PC:
Intel i5 CPU, 8GB RAM, Windows 8.1 (normally) (always pro), Office 2013 home and business (always retail version), NOD32 antivirus (never security suite), Acronis drive image home 2014 (this is your insurance), Small UPS (APC brand), 22" - 24" screen. Seriously consider a warranty upgrade to onsite.
Brand/suppler... well you will have to call me for that and it is significant.