Intel hit has been manufacturing more of the AMD chips which run on smaller speeds and use less power, but now it is no longer the case, because the Core chips run at a very high speed and are more powerful than the existing AMDs.
The Core Solo, the same as the core Duo, has been introduced at the same time, and they are both designed to be used specifically for laptops. However those made by Apple can be used in Laptops as well as in the desktops.
The names of those cores refer to the core which they use. The Core Solo has a single Core while the Core duo has double cores which are usable. However you should use only the Core Duo if the software you want to use is compatible with it, like Photoshop; with the Core Solo, one of its chips has been disabled. If you also want a chip with much speed, please choose the Core Duo because it has the highest speed among the other Cores. It has up to 20 percent more power that the normal AMD equipment.
The improvement in the Core Duo has challenged the AMD to produce more powerful chips and it forced the AMD to also reduce the price for some of its powerful chips. The problem now is how to choose among the above chips. Even if the price of the 64 bit AMD has been reduced, you have also to buy the 64 bit motherboard with it. This can be a great challenge for you if your motherboard is reliable and you like it. By considering reselling the motherboard, you can get some amount to use to buy the new one. Remember that all electronics loose their value when they are used, therefore the more you use the motherboard, the more it will loose its value.
However the better AMD option for your computer is the Core Duo which can be altered to suit your needs. It can be found in different ranges and you can choose the one you like the most. If you think it is time to change your AMD, go ahead and do it. Some people loose out by waiting for something hotter than those which are already in the market. The problem is that they wait too long. Get all the necessary information and decide what you want to do about your existing AMD.