Not as a standalone sentence. "However" can be used at the start of a sentence, but in that case it is indicating a contrast with something in a previous sentence, not with something later in teh same sentence. "However" can often be replaced with "but". If that makes no sense, the use of "however" may be incorrect.
You could, however, recast the sentence as:
Even though our school only has Apple computers, some students are more familiar with PCs.
Exception (to "however"="but"): there is another sense of 'however" as in:
However you do it, you must get it done.
Here "however" does not mean 'but" but rather 'in whatever way" or 'by whatever method", but that is not the case in the example in the question.