Changing the specifier in fprintf works with your suggestion... Thanks!

Code:
FILE *fp2;
fp2 = fopen("output2.txt", "w");
fprintf(fp2, "dwBytesRecorded = %d\n", lpBuffer[0].dwBytesRecorded);	

for (j = 0; j < (lpBuffer[0].dwBytesRecorded); j++) {
	fprintf(fp2, "[%d] <%x\n", j, lpBuffer[0].lpData[j]);
}

fclose(fp2);
returns
dwBytesRecorded = 348
[0] <0>
[1] <0>
[2] <0>
[3] <0>
[4] <0>
[5] <0>
[6] <0>
[7] <0>
[8] <ffffffc0>
[9] <ffffffd4>
[10] <1>
[11] <1>
[12] <0>
.
.
.