Some 78 percent of small businesses - nearly 20 million of them - regularly use the internet, including to make online purchases, according to a new JupiterResearch report.

Within five years, 82 percent of small businesses will have internet access, and 88 percent of them will be using broadband, according to "Market Profile: Understanding Online Small Businesses" report from Jupiter.

"Small businesses spent over $43 billion in 2005 in business purchases online," said Sonal Gandhi, JupiterResearch analyst and lead author of the report. "Their online-influenced off-line spending is likely to be considerably higher."

Some 90 percent of online small businesses have fewer than five employees and account for half of all small business online spending.

JupiterResearch defines online small businesses as companies with fewer than 100 employees, with decision makers regularly accessing the internet (regardless of location).