Reading DOS Structure from file and stuff into struct

private bool LoadFileIntoBuf() {
            bool bRv = false;
            using (FileStream fStream = new FileStream(this._sFilename, FileMode.Open, FileAccess.Read)) {
                int nLen = (int)fStream.Length;
                this._bBuf = new byte[nLen];
                int nRead = fStream.Read(this._bBuf, 0, nLen);
                if (nRead == nLen) bRv = true;
            }
            return bRv;
        }

private bool CheckDOSStub() {
            PEDumper.Win32ExeLayout._IMAGE_DOS_HEADER tmpDosHdr = new Win32ExeLayout._IMAGE_DOS_HEADER(0);
            byte[] bBuf = new byte[Marshal.SizeOf(tmpDosHdr)];
            Array.Copy(this._bBuf, bBuf, bBuf.Length);
            this._imgDosHdr = new Win32ExeLayout._IMAGE_DOS_HEADER(bBuf);
            bool bUnknown = false;
            switch (this._imgDosHdr.e_magic) {
                case Win32ExeLayout.IMAGE_DOS_SIGNATURE:
                    if (this._pSwitches[(int)ParamSwitches.Bits.Verbose]) Console.WriteLine("FOUND DOS Signature...");
                    break;
                case Win32ExeLayout.IMAGE_OS2_SIGNATURE:
                    if (this._pSwitches[(int)ParamSwitches.Bits.Verbose]) Console.WriteLine("Found OS/2 Signature...");
                    break;
                default:
                    if (this._pSwitches[(int)ParamSwitches.Bits.Verbose]) Console.WriteLine("Unknown Signature! {0:X2}", this._imgDosHdr.e_magic);
                    bUnknown = true;
                    break;
            }
            return bUnknown;
        }