Usually Dell Laptops come with built in Recovery Media. You need to boot into the Recovery Environment and then click the "Use a device". You should find something that says recovery or something like that.
Good Luck
I have a Xps 420 that came with a 375w PSU and I installed a Ge Force 210, It works perfectly. The Max RAM you can put in the 420 is 8GB, and SSD is possible (I am running a Samsung EVO 850 SSD and it also works w/ no problems.