Thank you for the additional information.
As an initial issue, I suggest that you check with two other types of professionals before starting your business.
First, because you are a Contractor, you will want to check with an insurance broker to see what it will cost to insure the business form you want to use. Some insurance companies will not insure Sole Proprietorships, which will mean you will need to incorporate or form an LLC to obtain insurance. I do not think you would have an issue obtaining insurance for a Contracting business and a landscaping business, but you may have trouble finding an insurance policy that also insures a PC Repair Business.
Second, once you know whether the business form you want to use is insurable -- and whether using one business form over another will have a substantial insurance savings -- check with an accountant to see what the best form for you to take will be, as far as taxes go. That really depends on what type of benefits you intend to give yourself.
With respect to how to have three different businesses, you have several options. You could separately form each entity, either as a Corporation (you will almost certainly need to be an S Corporation) or as an LLC. However, the most expedient -- and easiest to deal with, with respect to business filings and taxes -- is to form one business entity ([business name], Inc. or [business name], LLC for example) and file separate "doing business as" (dba) statements in the County you do business as.
The reason I put [business name] in brackets is that there is already a company called Allsource Solutions, and a website called http://www.allsourcesolutions.com/. By the way, the phrase "all source" is frequently used by programmers, especially when talking about open (free) source code, which means it is frequently searched by programmers.
As long as you are forming your business in a different state, you aren't violating corporate laws by using Allsource Solutions. However, as a practical matter, if you use the same name -- unless you spend a substantial amount of money on website advertising -- the other Allsource Solutions, or discussions about open source code are going to show up in a Google or Yahoo! search first. Therefore, you might want to find a name that is still descriptive but unique, so your customers can find you.
Good luck with your new venture.