Here is what I found on non compete clauses in Virginia:
Most states determine the enforceability of non-competition agreements under a so-called "reasonableness" standard. For example, in Virginia, a court will review the agreement under a three prong standard: (1) From the employer's standpoint, is it no broader than necessary to protect the company's legitimate business interests; (2) From the employee's standpoint, is the agreement unduly harsh and oppressive in precluding his or her ability to earn a livelihood; and (3) Is the agreement consistent with public policy? The agreement must be reasonable under all three prongs. Each agreement is considered under the particular facts of each case, depending upon the particular wording of the agreement at issue and the attendant facts of the case. As a general matter, such agreements are generally disfavored under the law of most states, and in such circumstances will be strictly and narrowly construed against the company and in favor of the employee. However, they are certainly enforceable if drafted correctly.
Each individual should carefully read and assess a proposed non-competition agreement before they accept an offer and submit their resignation to leave a job. Particularly in the sales field, a prospective employee should ask at the interview whether he or she would be expected to execute such an agreement.
Hope this helps!