Smagdy, note that if you're in sales of a product, that putting a G search box (or any search box for that matter) that has a "search the web" feature, that this is going to potentially push your potential customers elsewhere. Unless of course you're the only person that sells your product. After all, why would you want your possible customers to "search the web" for better deals?
On a side note, if you are in sales and can't have a "search the web" feature with the search: a while back for quite some time I tried to find a decent free "Advanced" site search (to replace Atomz which went from free to several hundred bucks per year), that did NOT place your competitor's ads on your pages and I didn't find anything. There were some free "SIMPLE" site searches with no ads, but they don't work very well and don't have things like exact phrase or "OR" searches, etc. When I found one that did have "advanced" search features the jerks would load it with ads from your competitors. Now I have no problem whatsoever with ads if it makes a product free, but when the ads are free advertising for those whom are in exact same field as you, that's just counter-productive and senseless.
I ended up using one I customize myself, it's a bought program. The problem with these types is that you have to update their index anytime you change your site whereas these other types are automatically updated either by pre-determined time period (set by you, or set by the search product and not changeable), or daily automatic updates in some versions. That I'm not sure about since I never looked into it because of the "search the www" feature it has. It may be possible to remove it, but then that still leaves you with competitor ads on the G results page.
If you have a lot of money and can afford it, Atomz's paid version is great. You can login it to it anytime you want to update the index. If you don't sell anything, then G's version is great (if, IF that is it has the same advanced search features as the main G SE). G also probably put ads on the result page from your competitors.