In a virtuous cycle, cool applications are also stoking demand for home networks. There’s Sony Corp.’s latest robot hound, AIBO Cyber-Blue which costs $1,299 and doubles as a watchdog, patrolling the halls and beaming pictures to a PC or handheld computer. A robot vacuum cleaner, iRobot’s Roomba, is also on patrol — doing the carpets.Unless you have a fat bank account, tying all these things together to create a connected home on a grand scale is nearly impossible. The Wollacks spent $125,000 on their system — far less than Bill Gates’s $50 million digital home, but beyond the means of most consumers, who on average are spending about $3,000 on such setups. What’s more, any keeping-up-with-the-Gateses digital dream can become a nightmare as you wade through a tangle of wires — or wireless software codes — and incompatible standards. For years, such barriers have stymied the smart-home concept. Indeed, the integrated home is still somewhat akin to Middle-earth in The Lord of the Rings, with factions constantly on the brink of war. “Right now, all we have are a lot of digital islands in the home,” says Bill Kenney, vice-president for online strategy at Sears, Roebuck & Co.