simply: it has more upgrades than the inspiron. xps are high performance laptops! inspirons arent really high performance.. however the inspiron 1720 is good enough to be classed as a high performance.
xps 1530 has higher heights of gaming, videos etc.. which would explain the extra costs you would be paying for the xps... personally i am not much of a gamer and the xps is ugly to me.. so i woul dgo for the 1720 even to its so BIG!!!! but if your are a huge video game fan! getthe xps :D
regards dinnerdash