interesting looking books :

 David Litchfield's Guide to Buffer Overflow Attacks
 by David Litchfield 
 Syngress ISBN: 193183623X

 Discrete Mathematics and its Applications, 5th edition
 Kenneth Rosen, McGraw Hill, 2003
 ISBN 007290330

 Computer Systems: a Programmer's Perspective
 Bryant, O'Hallaron, 2002, ISBN: 013034074X 
 (excellent amazon recommendations)
 Topics include: data representations, machine-level representations
 of C programs, processor architecture, program optimization, memory
 hierarchy, linking, exceptional control flow, virtual memory and
 memory management, system-level 1/O, network programming, and
 concurrent programming. The coverage focuses on how these areas
 affect application and system programmers. For example, when covering
 data representations, it considers how the finite representations
 used to represent numbers can approximate integer and real numbers,
 but with limitations that must be understood by programmers. When
 covering caching, it discusses how the ordering of loop indices in
 matrix code can affect program performance. When covering networking,
 it describes how a concurrent server can efficiently handle requests
 from multiple clients.

 Intro to Languages and the Theory of Computation
 John Martin

 Intro to Algorithms, 2nd Edition
 Cormen

 ** Introduction to the Theory of Computation
 by Michael Sipser 

Introduction to Automata Theory, Languages, and Computation (2nd Edition)
by John E. Hopcroft, Rajeev Motwani, Jeffrey D. Ullman 

Elementary Statistics, Ninth Edition
by Mario F. Triola
 - topics look good, but it's expensive; around $100
    * 864 pages ; Dimensions (in inches): 1.40 x 10.18 x 8.50
    * Publisher: Addison Wesley; 9 edition (March 4, 2003)
    * ISBN: 0201775700
    * In-Print Editions: Paperback (8th Sol Mn) | All Editions
    * Average Customer Review: 4 out of 5 stars Based on 21 reviews. Write a review.
    * Amazon.com Sales Rank in Books: #9,380
(Publishers and authors: improve your sales) 

Introductory Statistics with R
by Peter Dalgaard

Elementary Statistics
Bluman
(topics look good; uses Excel; about $50)
    * Hardcover: 848 pages ; Dimensions (in inches): 10.50 x 1.00 x 8.25
    * Publisher: McGraw-Hill Science/Engineering/Math; 5th Pkg edition (June 25, 2003)
    * ISBN: 0072880716
    * Average Customer Review: 5 out of 5 stars Based on 2 reviews. Write a review.
    * Amazon.com Sales Rank in Books: #146,304
(Publishers and authors: improve your sales)