Yes, but it means that the quoted price is 28% higher than the cost you actually pay. If they say a laptop will cost 1000, the actual cost is something like 750 for you. That means that higher prices on business laptops aren't entirely felt by the business customer - and if you are getting other stuff in the deal like on-site service, it's worth it.

In most places, you are able to use computers to decrease the profits used to calculate your tax if you're a business. The relevant law in the US is MACRS which allows you to claim depreciation of certain assets (which includes computers) as a deduction. This may be spread over a set period (5-6 years for computers) or potentially claimed all at once (via a section 179 deduction). Generally speaking, the amount you'll be able to deduct is approximately equal to the cost, if it's solely for business use.

In many contexts, "tax write-off" and "tax deduction" are used as synonyms. The IRS calls this sort of thing a deduction, so I'd say it's fair to call it a write-off too.