SAN FRANCISCO » The world’s two biggest personal computer makers are locked in a pricey struggle over which can move away from the PC business the fastest.

Hewlett-Packard Co. offered $1.5 billion yesterday for 3Par Inc., a company whose data-storage machines are designed for "cloud computing," or delivering services over the Internet. HP’s rival, Dell Inc., offered about $400 million less for 3Par last week, and many analysts and investors expect Dell to make a sweeter counteroffer.

HP’s offer comes just weeks after HP CEO Mark Hurd’s ouster over inaccurate expense reports and shows that the company is committed to continuing to grow through acquisitions, even without him at the helm.

The willingness to spend so much money on such an obscure company underscores how aggressively both companies are trying to move into more profitable markets than PCs.

Cloud computing is one of those markets.

It has caught on because many companies aren’t buying their own computer servers for certain tasks anymore.

Instead, they’re paying to have software they would have stored on those machines delivered to them over the Internet.

Companies such as Dell and HP are trying to take advantage of the trend by offering those kinds of cloud-computing services directly on a subscription basis, along with the equipment and software for customers to build their own cloud systems.

One problem, though, is the machines needed to run such operations are designed to be shared by multiple customers. Those machines need to ramp up or scale down their output quickly based on demand. Storage machines offered by 3Par could help cut the cost of operating those services because they are designed for such tasks.

Dell began the bidding contest last week by offering to buy 3Par for $18 per share, or $1.13 billion. HP responded by offering a third more, or $24 per share, for a total of $1.5 billion.

Investors, believing Dell will make a counteroffer, sent 3Par shares above HP’s offer price. Shares of 3Par closed yesterday at $26.09, up $8.05, or 45 percent.

But many analysts are worried that the price for 3Par has gotten too high, meaning HP or Dell would be overpaying for the company. HP shares fell 81 cents, or 2 percent, to $39.04. Dell shares were down 13 cents, or 1.1 percent, to $11.94.

Analyst Ben Reitzes with Barclays Capital called 3Par "a very good fit for HP strategically" but said the timing and price "may raise a few concerns."

Shaw Wu with Kaufman Bros. said 3Par’s shares have traded at around $10 for most of the year, so some investors are wondering why HP is now offering more than double that price.

"The biggest winners here are clearly 3Par employees and shareholders," he wrote.