How does a virus replicate ?

I have a desktop system and is quite old. I had purchased it around 2 and a half years ago. My system operates on windows xp home edition operating system and has an intel dual core processor in it with a 160 GB of hard disk space and 512MB of RAM. Since many days I am facing lots of issue in my system , it is working very slow and I get very frustrated whenever I use internet on my system , because the browser takes a long time to browse even simple websites such as google . Can any one please help me in fixing this issue as I am not used to such slow speed , because I used fast and powerful systems in my office.

Your system does not seem that old as you have a dual core processor in it, Intel has launched core i processor, it does not mean that dual core processors are obsolete or have become outdated. There are a lots of home users who use intel dual core processors. There might be some other issue in your system which is causing slow performance on your system. You have not mentioned any other symptoms that may give some hint to sort out the root cause of the performance in your system . So it would be better if you ca explain in a detailed way , what exactly is happening in your system and which Web Browser are you using currently ?

I am really sorry about that, I think I should have explained it in a better manner, had I given you all the details I think my issue would have reach at least some what closer to resolution if not completely. I am using a Google Chrome and it takes a hell lot of time to browse even a simple mail website or a search engine. As far as the symptoms are concerned my system works very slow and I get pop ups every now and then. My elder brother had warned me that these pop ups are the indications of virus attacks. He said that virus might have infected the registry and they have started to replicate among themselves. I did not get anything what he meant by those last few sentences, that replication part in particular. If any body knows what is meant by replication and how do virus replicate ? Eagerly waiting for your response ?

I think you would have downloaded something odd and funny that heavily impacted the performance of your system, yes your brother says correct, if you see pop ups , then definitely it is the virus attack. It seems that you do not A virus usually enters breaking a security, if the system does not have security then it makes a lot easier for virus to penetrate the registry. A virus is usually a malicious program that enters and attacks the system files most causing infection and replicates among themselves. By replication it means to expand in multiples. If you closely observe the code of a virus, you will see a payload sector. This sector is triggered by some event such as executing any .exe or setup file which is infected by the virus. Once the payload is triggered the replication starts and the virus infects the remaining parts as well causing Slow performance. Most vulnerable virus mostly attack the Boot Sector and may even result in crashing of the system. So it is always advised the never download any application or document file from an untrusted source or a file. If you think that oyu do not have any important document in your system you can reinstall the Operating system after formatting the partition.

There are various types of viruses. The most prominent of those is the Boot sector , which enters into the Master Boot record and replace the files stored in it with their own code and copy those files in some other parts of the hard drive. A stealth virus is a virus that tries to hide it's features and takes the form of a genuine file in order to avoid detection. I would suggest you to use an updated antivirus to prevent your system from virus attack.