Software

Windows left running Defragments HDD and this causes the Files stored on the HDD to fragment. This in turn causes the Read Write heads in the HDD to have to hunt around the Platters in the HDD to find the files necessary to load the unit.

The biggest result of Fragmented HDD's is Slow Loading and Program Excitation times.

Also if the HDD is nearly full it will slow things down considerably. So have you looked at how much space you have on the HDD free?

With Defraging I wouldn't suggest using the Windows Supplied Utility it's next to useless so use one of the Third Party Defragmenting Tools available.

Col

I already did 3 defrag sessions defragmentation normally, then tried IOBit Disk Defragger, and Piriform Defraggler, but none worked. There's a lot of space for the default drive (C:\) about 30 GB more and the partitioned drive has about 20 GB left.

Also, this unit doesn't have any much applications installed on it, only the basics like an antivirus (AVG Pro), MS Office 2007, CCleaner, IOBit softwares, USB Disk Security, Scanner program for its Canon LIDE 100 scanner, Windows Live Messenger, Adobe Reader, and essential applications for proper internet explorer use (like Flash, Shockwave, Java, etc.). It's also fully updated with the proper Windows Updates.

It is likely riddled with malware. I suggest a full reformat and reinstall of Windows. Just start fresh.

Put in the maximum memory that you can, in your case 4gb of memory. It will make your system run more smoothly and a little faster.
Also a hdd with a 32mb memory added will help also.
Windows will only see just over 3gb of the memory on your motherboard unless you get (or have) the 64 bit version.

If you don't have a big malware problem, a really big one, maybe you have hardware problems.

@Sinister:
It's not a malware, I already scanned the whole thing with every effective scanner I have (Malwarebytes, Stinger, Sality Killer, Sality RegKeys)

@Peconet
Tried amping the Ram up to 3GB (the only 1gig ddr I have left) but still doesn't work. It's still super slow loading.

@logins:
Definitely not a malware problem as I stated above, I've scanned the whole system and nothing comes up. But I am trying to determine if it's a hardware problem. I'm betting it's the HDD, it does make some light clunky noises, probably about to fail soon.

Have you tried looking at "Event Viewer" or "Performance Monitor?" They'll tell you what the system is doing, what's running, what resources are being used etc. Use "Help" to find it. An additional thought: If you're running more than one AV program, the two AV's may perceive each other as a virus attack. You can confirm this in "Performance Monitor". If CPU usage rises rapidly to 100%, then falls off, then recycles, you probably have this situation. Remove one of them. You can also find out if one of the CPU's has failed using this. Another thing to check--tedious but effective--is to remove software, check the system speed, then reload and recheck. In the days of Win98, this was a common issue; much less so today but still possible. Product plug: I recently bought a hard copy (3 license--1 year) of AVG's "PC TuneUp 2011" at Fry's. Wow!! I've liked their AV and have used it for several years, so felt comfortable with this. I use it with both XP and Vista. It finds duplicate files as well as the usual stuff and it's a very user-friendly program. With all of that said, this just may come down to a hardware issue, but you'll have a better feel for the system.

Have you tried booting into "Safe Mode" minimal drivers are loaded and boot up should be about normal, if you still boot slow, run a memory check , and a hard disk check.