Can your dell inspiron laptop 1545 run sentence Intel Pentium Dual Core T4500 processor 2.3GHz 800MHz Fast System Bus 1MB Cache 3GB DDR2 SDRAM memory 250GB hard drive Intel graphics4500

That should be more than good enough to run World of Warcraft in medium quality mode. However, just be mindful that even with really good computers, there is always the chance of freezing/crashing when entering densely populated areas of Azeroth (ie. Dalaran). It is not just the speed and power of your computer, but also the power and strength of your internet connection to the server. You can have the best computer on the face of the earth, but if your internet is lousy, you just might have bad experiences.