|"I bougt a new DELL R15 a few days ago"|
It must have come with Win7 preinstalled, why did you remove it? XP is almost 10 yrs old & I'm sure doesn't contain the device drivers for your modern laptop. In fact, there may not even be XP drivers available. Far too many people think that all you have to do is just install Windows from the disc & everything will just automatically work. Unfortunately, that is rarely the case. You need to idenify all the major hardware devices (chipset, video, audio, ethernet, wireless, etc), do a search for the drivers, then download & install. Either that or go back to Win7. I'm sure you created the system recovery discs before you wiped the drive, right?