javascript against jquery

I am programmer. I worked in programming sphere C++ C#. But recently my interests change more to Web programming - ASP.NET and PHP.
I worked for about six years to develop my knowlege in WEB programming. Some sites i ushered into world of internet  .

Office Partitions in Moscow(100peregorodok company)
Art and Painting(site for them who wants to learn how paint )
Design and company style
Real Estate Korolev(Moscow)

The point i want to concern here is what is the best - working with rude jvascript or using some plugins like jquery.

For most who worked with javascript and jquery the answer is clear -of course jquery. But do not do a haste.

When I worked on an-gbn project I stumbled on some mystic fiture when using jquere functions.

This problem apeared only in ie browser.

Load an-gbn.ru and see line 740 in code.
Ther will be :
 //$('#descript').html(str12);
 document.getElementById('descript').innerHTML = str12;

Jquery function $('#descript').html(str12); going wrong in ie browsser and I have to change it into javascript -  document.getElementById('descript').innerHTML = str12;

What s the matter ? After jquery execution in ie browser we have the wrong string that will be display on the screen.

For example initial string in unicode(cirylic) - купить квартиру в Королеве.
Then on the screen we may have - купить квар?ртиру в Королеве.
Very nice? Yes. Like something interupted execution of jquery and add two symbols - ?(it is the symbol that browser can't display) and р(that it is the last symbol before interuption, it is repeated)

And ofcourse the only option for me is using javascript in this case.
If anyone knows what the matter go and write some remark.