You are correct in that the OP has code that meets dragonchild's First Criterion of Good Coding. However, I would actually argue that the OP should convert to Win32::IPConfig, for the following reasons:

1. OP would learn more about the Win32:: namespace
2. OP would learn why it is useful to use said namespace
3. Maintainer(s) (which might include OP) won't have to deal with hand-rolled code (and the bugs that go with no peer review)
4. If ipconfig changes (as it probably will), Win32::IPConfig will (should?) change with it
5. Should ipconfig be different on different Win32 machines, Win32::IPConfig will (should?) handle that transparently

Those reasons boil down to meeting the Second Criterion of Good Coding.

1. Code should do what it needs to do.
2. Code should be both easy and safe to modify.

1. Code that meets #1, no matter how poorly written, is "good".
2. Code that meets both #1 and #2 is "great".
3. Code that meets #2, but not #1, is worthless.