Let's try to stick to the original code, thus activate the fix of #62 only for 64 bit builds.

Eigen/src/Core/arch/SSE/PacketMath.h

diff --git a/Eigen/src/Core/arch/SSE/PacketMath.h b/Eigen/src/Core/arch/SSE/PacketMath.h
index c1d7e57..f588a86 100644
--- a/Eigen/src/Core/arch/SSE/PacketMath.h
+++ b/Eigen/src/Core/arch/SSE/PacketMath.h
@@ -220,12 +220,17 @@
 template<> EIGEN_STRONG_INLINE void ei_pstoreu<float>(float*  to, const Packet4f& from) { ei_pstoreu((double*)to, _mm_castps_pd(from)); }
 template<> EIGEN_STRONG_INLINE void ei_pstoreu<int>(int*      to, const Packet4i& from) { ei_pstoreu((double*)to, _mm_castsi128_pd(from)); }
 
-#ifdef _MSC_VER <= 1500
+#if (_MSC_VER <= 1500) && defined(_WIN64)
 // The temporary variable fixes an internal compilation error.
 // Direct of the struct members fixed bug #62.
 template<> EIGEN_STRONG_INLINE float  ei_pfirst<Packet4f>(const Packet4f& a) { return a.m128_f32[0]; }
 template<> EIGEN_STRONG_INLINE double ei_pfirst<Packet2d>(const Packet2d& a) { return a.m128d_f64[0]; }
 template<> EIGEN_STRONG_INLINE int    ei_pfirst<Packet4i>(const Packet4i& a) { int x = _mm_cvtsi128_si32(a); return x; }
+#elif (_MSC_VER <= 1500)
+// The temporary variable fixes an internal compilation error.
+template<> EIGEN_STRONG_INLINE float  ei_pfirst<Packet4f>(const Packet4f& a) { float x = _mm_cvtss_f32(a); return x; }
+template<> EIGEN_STRONG_INLINE double ei_pfirst<Packet2d>(const Packet2d& a) { double x = _mm_cvtsd_f64(a); return x; }
+template<> EIGEN_STRONG_INLINE int    ei_pfirst<Packet4i>(const Packet4i& a) { int x = _mm_cvtsi128_si32(a); return x; }
 #else
 template<> EIGEN_STRONG_INLINE float  ei_pfirst<Packet4f>(const Packet4f& a) { return _mm_cvtss_f32(a); }
 template<> EIGEN_STRONG_INLINE double ei_pfirst<Packet2d>(const Packet2d& a) { return _mm_cvtsd_f64(a); }