(Reuters) -- Hewlett-Packard Co's earnings fell nearly 44 percent and the world's No. 1 computer maker forecast a second-quarter profit below Wall Street estimates as it struggles with weak sales of PCs and printers.

The storied Silicon Valley company, which has been trying to move past the internal upheaval that marked 2011, posted quarterly sales declines in three of its key units: personal computers, printers and enterprise equipment.

Chief Executive Meg Whitman, a veteran Silicon Valley executive who took the top job last September after the firing of Leo Apotheker, has been trying to turn around HP's sprawling businesses.

Last year was a turbulent one for the company, marked by strategy flip-flops, executive churn and the ouster of Apotheker after less than a year in the top job.

On Wednesday, HP reported net income of $1.47 billion for the fiscal first quarter, or 73 cents a share, down from $2.6 billion, or $1.17 a share, a year earlier.

Excluding items, HP earned 92 cents a share, above the average analyst estimate of 87 cents according to Thomson Reuters I/B/E/S.

Revenue fell 7 percent to $30 billion, slightly below Wall Street's consensus estimate.

Sales from the personal systems group, encompassing PCs, declined 15 percent while revenue from its bread-and-better printing group fell 7 percent, hurt by weak consumer demand.

Sales of enterprise servers, storage and networking equipment - usually a bright point for HP - also fell 10 percent.

Looking to the current, fiscal second quarter, HP said it expects non-GAAP diluted earnings of 88 to 91 cents a share, below Wall Street estimates.

It reiterated its full-year non-GAAP earnings outlook of at least $4 per share.

HP shares slid to around $28.65 in after-hours trading. They shed 1.39 percent in the regular session to close at $28.94 on the New York Stock Exchange.

(Reporting By Poornima Gupta; editing by Richard Chang and Andre Grenon)