Sun Microsystems (JAVA) 10-Q 2006 Q1 Quarterly report

EXHIBIT 15.1

November 2, 2005

The Board of Directors and Stockholders, Sun Microsystems, Inc.

We are aware of the incorporation by reference in the Registration Statements (Form S-8 Nos. 33-18602, 33-25860, 33-33344, 33-38220, 33-51129, 33-56577, 333-09867, 333-34543, 333-34651, 333-38163, 333-40677, 333-40675, 333-59503, 333-62987, 333-65531, 333-67183, 333-72413, 333-86267, 333-89391, 333-90907, 333-35796, 333-45540, 333-48080, 333-49788, 333-52314, 333-56358, 333-59466, 333-61120, 333-62034, 333-68140, 333-73218, 333-98097, 333-100189, 333-101332, 333-101323, 333-108639, 333-109303, 333-111968, 333-114550, 333-114551, 333-122586, 333-127063, 333-128324 and 333-128325; and Form S-3 Nos. 333-81101 and 333-63716) of Sun Microsystems, Inc. of our report dated November 2, 2005 relating to the unaudited condensed consolidated interim financial statements of Sun Microsystems, Inc. that are included in its Form 10-Q for the quarter ended September 25, 2005.

Pursuant to Rule 436(c) of the Securities Act of 1933, our reports are not a part of the registration statements prepared or certified by accountants within the meaning of Section 7 or 11 of the Securities Act of 1933.

Very truly yours,

/s/ Ernst & Young LLP