What exactly the difference between Sun Certified Programmer for the Java 2 Platform, Standard Edition 5.0 (CX-310-055) and Sun Certified Programmer for the Java 2 Platform, Standard Edition 1.4 (CX-310-035). Which one is the better course to take.. Please let me know.
"Java 2 Platform Standard Edition 5" (J2SE5) corresponds to the "Java 1.5" programming language (the numbering difference is just marketing-speak), so "SCJP 1.5" and "SCJP 5" are pretty much interchangeable terms around here.
Anyway, SCJP 1.5 (310-055) is for a much more recent version of Java than SCJP 1.4 (310-035), so you definitely want to take the SCJP 1.5 exam unless you have a special reason to limit yourself to 1.4. After all, the current version of Java is now 1.6, which means the market value of a new Java 1.4 certification is probably on a sharp decline.
The bad news? The SCJP 1.5 exam is regarded as substantially harder than SCJP 1.4, due to the many new language features introduced in Java 1.5. But you just have to accept this as the inevitable learning curve in becoming a certified Java programmer. Ignore any advice you may hear to do the SCJP 1.4 exam just because it's easier. Although you may get your certification more easily that way, you're going to be in for an awkward time when your next job interviewer asks you why you chose the 1.4 exam instead of the 1.5.
For more info, refer to this site's SCJP FAQ. You may also want to compare the official exam objectives for SCJP 1.4 and SCJP 1.5.