Vostro 3450 - Wirelss Connection Problem - Is it System Issue?

Please tell me what my next step should be.  Daughter is at college with brand new Vostro 3450.  Was working on school network during summer but now the system drops the connection multiple times during the day.  She gets message "limited connection".  She runs the Troubleshooting which then allows her to connect and 30 minutes later the connection is dropped again.  The laptop works fine when connected to the internet via the ethernet cable.  Here is what has been done by the IT support at the school.

1 -  Deleted the Intel wireless utility as they thought it was "fighting" with the Windows software for control over the wireless. 

2 - Increased the power for the wireless card to "high performance".

3 - Reinstalled Windows 7 to eliminate that there is a software issue.

4 - Replaced the Intel Wireless Card with new part sent by Dell.

Now the IT supports recommendation is to "get a new system" and that perhaps the Vostro's wireless card is "not compatible with their network".  For Dell computers they sell the Latitude to the students.

My daugther likes the Vostro.  She doesn't want to give it up.  Wants the system to work.  She had the laptop during the summer session and had problems with connection.  The Windows software was reinstalled thinking there was a virus (although no evidence of one) and then she had no connection problems for the whole summer.  She came home for 2 weeks and returned  back to school and then the system would not work again.

I don't know what to do.  Can I buy a USB wireless adapter for her to temporarily use until I can figure out how to fix this problem.  Personally, I think there is a design flaw with the vostro.  The school is thinking maybe the laptops wireless card is not compatible with their network and do not reocmmend getting another Vostro.  Is there anything else I can have done with this system?

thanks Gidget