Microsoft Corp. has broken into the banking industry's Top 50 with its  Windows NT operating system for retail banking. 
Attacking a historical stronghold of International Business Machines  Corp., Microsoft plans to announce today that Crestar Financial Corp. of   Richmond, Va., is the first U.S. commercial bank of its size to deploy   Windows NT throughout its branch network.     
  
Crestar has already converted its 400 branch servers in Virginia,  Maryland, and the District of Columbia from IBM's OS/2 operating system. 
The bank also expects to have Microsoft's Windows 95 operating system on  1,800 branch-platform workstations by the end of August. 
  
Microsoft's aggressiveness in selling desktop software has some bankers  concerned it is after the home banking market. Yet the Redmond, Wash.,   software giant is easing more and more of their core computer functions   toward its Windows technology.     
The $22 billion-asset Crestar, the 34th-largest banking company, may  only be the first wedge Microsoft is driving into the industry's top tier.   Citicorp, Chase Manhattan Corp., and NationsBank Corp. have been deploying   or are testing the Windows operating system at branches or call centers.     
Mentis Corp., a Durham, N.C., research firm, has projected that 53% of  banks with deposits exceeding $1 billion will be running on Windows NT by   yearend 1998, up from 8% at yearend 1996.   
  
Attempting to refute the empire-building charges, Microsoft stresses its  role as a "core-technology" provider that relies on other developers to   implement the systems banks buy.   
Michael S. Dusche, Microsoft worldwide financial services industry  manager, called the Crestar commitment "momentous. It most importantly   validates our business model that no one manufacturer can provide the   hardware, systems software, and applications software, so there's a   definite need for partnerships."       
Crestar's direct supplier is Argo Data Resource Corp. of Dallas, a  Microsoft CSD, or certified solution developer. Argo's BankPro software is   also in use at NationsBank, Barnett Banks Inc., BankBoston Corp., and   CoreStates Financial Corp.     
"When Crestar decided to go with a teller automation system, it also  wanted to move to the Windows environment," said Bala Shagrithaya, vice   president of systems at Argo. "Essentially, we are re-using all of the   applications we developed for OS/2."     
  
This is the first BankPro implementation on Windows NT, which Mr.  Shagrithaya said is "a more scalable and dominant operating system. We see   most of the new implementations being NT-based as opposed to OS/2-based."   
Crestar is also piloting Argo's BankPro with Windows 95 at teller  workstations, connected to the same Windows NT server, at five branches. 
All 2,000 teller stations are to be upgraded by the end of the second  quarter next year. A related project, computer-telephony integration in   call centers, is to be concluded in mid-1998.   
"Windows 95 is our corporate standard as we move to link more branches  together in a wide-area network," said David Holman, Crestar senior vice   president of branch operations.   
The bank worked "in partnership with Argo and Microsoft to be the  initial deployer of an NT-Argo solution," said Mr. Holman. "We thought a   long-term solution would achieve stability and the necessary internal   compatibility. NT was the one to go with."     
Mr Holman said by the time Crestar has upgraded all its servers and  workstations, it will have invested $15 million to $20 million in Windows   NT.   
"Crestar is taking advantage of an operating system that lets it build  one set of applications for the branch, call center, lending, and Internet   banking," said Mr. Dusche. "What we offer is clearly substantially cheaper   than proprietary systems."