Hi Lorraine,
OK..Lets start. 256Mb is really the bare minimum required for running Windows XP, so a memory upgrade will not do any harm.
You mention that you have Norton Anti Virus installed, do you pay the annual subscription fee for file updates? I doubt it (because most people don't) which means that the virus database that Norton is using is at best about 2 years out of date, so lots of scope for something nasty to be lurking on there.
Any Anti Virus program is only any use if you keep it up to date. Mine is updated daily to hopefully ensure complete protection.
So long as your laptop has an adequate number of USB sockets for the devices that you need to connect, then there should be no need to buy additional adapters. Even if the printer / scanner is USB 2.0 compliant and your laptop is USB 1.1 (which I thinkit will be based on it's age) the worst case is that data will not transfer as quickly from your laptop to the printer / scanner as it would if both ends were USB 2.0. I doubt you would notice the difference anyway.
I would suggest as a start making sure that the computer is 100% clean of Virus and Spyware 1st. Then it would be good to get an extra 256Mb or RAM in there or more if it will take it.
There are plenty of good FREE programs available to help. I can recommend AVG Free as a good and simple Anti Virus solution, they also do free versions of Anti Spyware and Rootkit software now too, but others such as Spybot and Adaware are very good in their own rights.
The most difficult thing is often getting rid of Norton Antivirus
If you don't feel confident in doing this then I am more than happy to show you what to do or can take the laptop and do it for you.
I always try to get people to do it for themselves though as it means that they can keep on top of things in the future.
Please PM me if you want me to do this.
Potdog.
EDIT: Forgot to add, please give me the model name of the Laptop so that I can find out how much memory can be installed. Cheers.