Your brother is correct about possible upgrades for a 6 year old computer. It all depends on what you have at present, in terms of memory, hard-drive capacity, motherboard and other items. The list can be extensive.New parts might not be at all compatible with some existing parts, which would add further problems.
Personally I have upgraded three 'older' computers, and in each case it didn't solve the issue of trying to turn old into new. Looking at some of the latest systems and the prices being asked, plus a 12 month or more warranty. Then I would suggest that you look at purchasing a new system, and perhaps using the older unit as a spare.
Do you know what your Packard Bell contains. If not, then download something like Belarc, Fresh Diagnose, SIW,PC Wizard 2008, CrystalDiskInfo (all free!), which should tell you what your computer contains. Then post the answers on the forum, so that other members can possibly advice.