Sun Microsystems' high-profile president and chief operating officer Jonathan Schwartz has struck a raw nerve with his inflammatory Weblog entries which has led to Hewlett-Packard sending a letter of demand to Sun to put an end to the commentary.

HP has confirmed a letter was sent earlier this week demanding Schwartz stop using his blog to comment on HP's strategic direction.

The HP spokesman declined to provide any details about the content of the letter except to say it specifically refers to Schwartz's Weblog commentary about HP.

Schwartz has not been shy with his statements about the HP's strategies, particularly regarding its Unix operating system, HP-UX.

In a blog entry, dated August 18, Schwartz referred to HP-UX as a 'dying' operating system.

"To me, HP's problems spawn from the death of... their operating system, HP/UX," Schwartz wrote. "Like IBM, they've elected to ask their customers and ISVs to move to Red Hat Linux or Microsoft Windows on x86 systems. And if you're an ISV, how does that differentiate HP? - they're a box vendor. If you're a customer, where does that leave you with your HP/UX investments? Facing untimely change - with a vendor no longer in charge of their OS."

Naturally, HP vehemently denies such claims and views them as verging on defamation to the extent that it feels a formal letter is in order. Schwartz is also of the opinion that "our commitment to Solaris highlights the demise of HP/UX".

"HP/UX won't even run on HP's own industry standard servers," he wrote. "As an ISV told me last week, 'I come to Sun, you tell me to write to Java, then write to Solaris. Clear as a bell'. If you're an HP customer or ISV, have some fun, ask your HP rep the same question: what should I write to?"

This comes at a time when HP has announced that it has gained more than 200 Sun server customers over the past 18 months.

"In financial services alone, HP has won more than 40 significant deals from Sun Microsystems," a HP media release stated. "The 200 HP customer wins include Bank of Bolivariano of Ecuador, Belkin, Dynamic Net, Forbes.com and The University of Hong Kong."

Belkin's CEO Chet Pipkin said in the release: "When we replaced Sun Solaris with HP to run our business-critical systems, we were able to significantly reduce our total cost of ownership and deliver an average performance increase of 250 percent."

Schwartz has also taken aim at HP's decision to move to Intel as its standard architecture.

"While HP tells its customers to 'change' (we're still not sure 'to' what, I'm more comfortable with the 'from' part)," he wrote. "Because no matter what the ads say, what customers don't want is unnecessary... change."