Is there an easy way to convert from a byte array to integer? Is there an equaly easy way to convert from integer to a byte array?

Currently what I do for a byte array of length 2:

System.Int32 iValue = 42000;
System.Byte[] bValue = new System.Byte[2];

bValue[0] = Convert.ToByte(iValue/256);
bValue[1] = Convert.ToByte(iValue%256);

System.Int32 iRetVal;
iRetVal = Convert.ToInt32(Convert.ToInt32(bValue[0]) * 256 + Convert.ToInt32(bValue[1]));

Now this isn't a lot of work for byte[2] but it will get kinda messy for byte[4]. I have got it working for byte[4], but I was wondering if there was a simpler/built in (one-liner) way of doing this.

Any help would be appreciated.

Thanks,
Einar