Or you could make a backup for the files you want to keep and use the restore disk, to set every thing back to factory setting, this will DELETED every thing on your laptop.
The problem is this, you had windows Vista on the system, used windows 7, then deleted windows 7 to go back to windows Vista, you wil have reg problems as windows dose not like to clean it's self.
You can get software that will let you know how big your reg is, and some that will clean it also, this is somthing that can mess up your computer if not done right, but try CCleaner, this may help, and yes the Start up programs will need to be looked at as well, also deleteing tem internet files, defraging the HDD and so in if these do not work, restor the LapTop and start a fresh, I do this with the DeskTop and LapTop ever 6 months or so, it's just better for me to do it this way, and I have a back up and a back up of the 1st one, do dose not matter about saving every thing and the setup is ghosted as well meaning that it only takes about 1 hour for me.
these are just something you can be trying before buying a new laptop, but remember to back up every thing you want to keep as it will be lost, you can not hold me responcible for it going wrong and or any damage to your laptop.