I'm going to assume since you want a laptop your old computer is a laptop.
There is NO WAY you need a "NEW" computer. If you buy a new computer your are wasting your money. I would say the chances of your computer needing a complete replacement is very very low (unless it's been dropped).
Computer freezing is almost ALWAYS due to a bad hard drive. 2 years is within the range of a laptop having a drive die (early...but not too crazy).
As Gordon has suggested I would bring it to your local repair show (NOT BEST BUY). Have them take a look at it. If it is the hard drive you're looking at a few hundred bucks to replace it and have windows re-installed. Depending on how much storage you need I would also suggest going with a SSD drive. Not only are these more reliable and less prone to damage they are also WAY faster than a spinning drive. The downside is they are more expensive, but if you can live with 256GB you can get one for about $200 (plus the cost to have it installed and the OS re-installed).
What is the EXACT model of your computer. I'll try to see how easy or difficult it is to swap the drive out yourself. Some laptops will simply have a little door you need to open to swap the drive out. If this is the case it's about as difficult to fix as Legos.
If you want to fix it yourself you're going to need to re-install windows and your programs. Make sure you have your re-install disc. If you don't have that I might be able to get one for you. You'd just need your serial number to get yourself up and running.
Don't be afraid of your computer. Fixing it is very easy. When I first started working on computers it was because I couldn't afford to pay someone to fix my computer. I was scared shitless that I was going to completely ruin it, but didn't have a choice. Once I got in there and did the work I discovered that there wasn't much too it. Yes you need to be careful and yes you need to do some reading first, but it's not a car. More often than not you're going to unplug whatever is broken and replace it with a working part.