**Exhibit 31.1**

**CERTIFICATION PURSUANT TO 17 CFR 240.13a-14(a)**

**PROMULGATED UNDER SECTION 302 OF THE SARBANES-OXLEYACT OF 2002**

I, Mikel H. Williams, certify that: 

1. Ihave reviewed this annual report on Form 10-K for the fiscal year ended December 31, 2007 of DDi Corp.; 

2. Based on my knowledge, this report doesnot contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered bythis report; 

3. Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all materialrespects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report; 

4. Theregistrant’s other certifying officer and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as definedin Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have: 

(a) designed such disclosure controls and procedures, or causedsuch disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularlyduring the period in which this report is being prepared; 

(b) designed such internal control over financial reporting, or caused suchinternal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance withgenerally accepted accounting principles; 

(c) evaluated the effectiveness of the registrant’s disclosure controls and procedures andpresented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and 

(d) disclosed in this report any change in the registrant’s internal control over financial reporting that occurred during the registrant’sfourth quarter ended December 31, 2007 that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting; and 

5. The registrant’s other certifying officer and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to theregistrant’s auditors and the audit committee of the registrant’s board of directors (or persons performing the equivalent functions): 

(a) all significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant’s ability to record, process, summarize andreport financial information; and 

(b) any fraud, whether or not material, that involves management or other employees who have asignificant role in the registrant’s internal control over financial reporting. 

 

Date: February 29, 2008