The first thing is to look at the monthly cost of the loan. The one from the company is interest free. While it is unlikely that a bank will have a zero percent loan, you will also have to look at what the seller will offer.
The next thing to look at is the term of the loan. When comparing two loans with the same interest rate the shorter term loan will cost more per month. Many times when an auto dealer offers a zero percent loan they also have a very short term: 12-24 months; Many people can't afford the monthly payments with that short a term.
You said you could afford to save the other $2000 in about six months. That means you could set aside $333 a month to do it in six months. If the loan from the employer has a term longer than 6 months you should be able to afford the loan. Keep in mind that the employer will probably be taking the money right out of your paychecks.
You do have to look at the conditions attached to the loan. What does accepting the loan do to your employment situation? If you leave early do they want you to pay it back in 30 days, or will they take the rest from the final paycheck, or do you have longer?
You do have to look at the term of the loan, and see if you can pay it off early. If they require a 12 month term can you end it earlier, or change the monthly payment to end it early? The reason why you care about the term is that if the term is 24 months then after a year you still owe them $1000; which if you have to pay back immediately if you quit, it may make it hard for you to leave the company.
A minor note: They probably are not reporting it to the credit reporting agencies therefore it wont help your credit score. This is probably not a big issue since you are considering going without a loan.