FutureLink Corp., an Irvine-based provider of computer-application hosting services to businesses, agreed to acquire closely held VSI Technology Solutions for $26.5 million in cash and stock, gaining clients in the U.S. mid-Atlantic region. The purchase price includes $19.5 million in FutureLink stock and $7 million in cash. Beltsville, Md.-based VSI is a reseller of Citrix Systems Inc.'s application server software, which runs servers and other computers. It has 75 employees and annual revenue of $9.7 million. FutureLink provides companies with off-site, Internet-based computing services, saving them from having to individually install and upgrade applications on employees' PCs. FutureLink now operates in Canada and the Southeast and Southwest. FutureLink rose 3 cents to close at $23.50 in over-the-counter trading.