Are your old shoes comfy? If you can't get a gait analysis where you live, try Nike customer services and you may be able to find out whether your current shoes are neutral or extra-support or whatever. My running shoes are also really old and Nike were really helpful and let me know the model name for the current equivalent of my shoes.
Gait analysis really good. I have never run in my life but decided I needed to get off the sofa. Went and got running shoes from a gait analysis place (OK I'll be honest here - the shop had parking outside - I wasn't up for taking the 1 and 5 year old on a bus), tried several, bought a pair two sizes bigger than I take in regular shoes on their advice and I can honestly say when I run/lollop I don't notice my feet at all, they are very comfortable and my feet never hurt or ache afterwards. Worth it.