The LG IPS237L-BN is an excellent monitor, that's definitely worth your consideration if you need a new 23-inch screen. That said, its performance is not quite on the level of the 27-inch IPS277L-BN. This is true for the brightness from different viewing angles, the colour temperature, colour fidelity and gamma values.
Slow computer got you down? Maybe a hardware upgrade should be in your cards, if so this guide to the Fundamentals of Upgrading a PC is an invaluable read. PCSTATS Tips