I have an Inspiron E1505 Dell Laptop. With Windows XP Media Center Edition. Version 2002 Service Pack 3. I have -

Genuine Intel(R) CPU
T2300 @ 1.66GHz
98-MHz, 504 MB of RAM

Is that everything you needed? Does it help?
How big is the hard drive and how much space is remaining?
Absolutely you need an Anti-virus program. Two very good FREE ones are Avira and Avast Pick ONE, install it, update it and run a Full Scan with it. Allow it to remove all that is found.
Judy