well, Tat, being IT illiterate like yourself I can only suggest ...... have you been into your programmes to see what you can get rid of? If you aren't sure how to do this I will let you know on A'Book. Inserting more RAM. Other than sounding painful/ promising depending on your outlook, involves buying more memory. But I don't know how!
In Windows 2000 and XP to see whether you need more RAM you can do a simple test: Right click the task bar (the grey bit at the bottom of the screen) and select "Task Manager..." (alternatively, press ALT + CTRL + DEL and on the security screen press "Task Manager") and on the performance tab see whether the Total Commit Charge (k) is greater than the Total Physical Memory (K). If it is you will need to buy then install more RAM. The reason is that you don't have enough memory so the computer is using your hard disk to "page" memory which slows it down.
try a program called adaware 6 from lavasoft ( http://www.lavasoftusa.com/software/adaware/
). One of the most common causes of slow down is the presence of trojans or data miners. This free prog cleans your drive of all unwanted nasties. I would also recommend a defrag (START>ACCESORIES>SYSTEM TOOLS>DISK DEFRAGMENTER) as this will help your pc find all its files that little bit easier...