Differences between CAPICOM TripleDES and System.Security.Cryptography TripleDES

Question

I'm trying to move away from using CAPICOM since I can no longer use it (64-bit Windows 7 machine).

The existing code for using TripleDES is like this:

EncryptedDataClass cryptic = new EncryptedDataClass();
cryptic.Algorithm.Name = CAPICOM_ENCRYPTION_ALGORITHM.CAPICOM_ENCRYPTION_ALGORITHM_3DES;
cryptic.SetSecret(secretKey, CAPICOM_SECRET_TYPE.CAPICOM_SECRET_PASSWORD);
cryptic.Content = stringToEncrypt;
encryptedString = cryptic.Encrypt(CAPICOM_ENCODING_TYPE.CAPICOM_ENCODE_ANY);

The only information supplied for the encryption is the secretKey. And the secretKey comes out to be about ten bytes. Is there a way use the .NET class to do the same encryption. Note: this is used to verify connection to a web service that will still be using CAPICOM. Any help or ideas are greatly appreciated.