Given that the XPS M1530 were designed as mid range gaming laptops when they were made I'd say if it still plays the games or does what you want it to why upgrade to a new machine and spend even more money.
The SSD is well worth the money for the speed you'll get and if you ever do upgrade to a newer laptop you could easily make the SSD over, replace it with another standard HDD and sell the XPS that way to recoup some of the upgrade cost. Also SSD is the best bang for the buck right now with HDD prices being crazy from the Thailand floods earlier this year.As for the ram upgrade if you only have 2GB I would higly recommend going to 4 or even 8 if your budget allows it. The speed improvement you'd see with that + the SSD would make it...