Is this job a deadend?

I'm currently a student in Computer Science with around 2 semesters left. Last October I found and part time job doing some web development for a small company. It pays well enough and the hours are good, but I'm wondering if it's taking me down a useless path due to the technologies used.

I work on the internal website which was originally written in 2005 or so. It's all written in Classic ASP (JScript) and is the biggest mess (spaghetti code, no design considerations). The db that powers the site is SQL Server 2005 and the server is IIS 5.0

Many times I've considered asking to rewrite it in something more modern that is receiving updates. The problem with that is this site might be phased out entirely if the company decides its time to implement a real ERP system. They are growing and I feel like this is a good possibility. If that were to happen my job would most likely transition into implementing some open source ERP. I'm the only developer at this place and am supervised by the IT guy who does everything else (db admin, external site admin etc..)

I'm just wondering how beneficial this is to my future career and if I should get out. I like this job because it's laid back and eliminates some stress looking for an internship this summer. The problem is the future. I feel like I'm not gaining valuable industry experience here (aside from having a job in general). I'm not learning anything that is still being used.

Am I wasting my time here?