Best way to handle 301 and Google

[rjwmotor]

I have a question about the 301 redirect and Google. I run a php driven shopping cart and am looking to upgrade it to the newest version. However, main category links in the upgrade have all changed. All of my current links rank pretty well in G and am very concerned about how upgrading would affect rankings. The new links are much more se friendly and the reason for upgrading is the current cart and is beginning to become outdated and unsupported.

1)Would using a 301 redirect on these old links to the new "SE" friendly links be a huge gamble on my Google serps?

2) The creators have made it so you could still access the old url's also. I contacted them about a fix to leave the old url's unchanged but to no avail. I alos thought about 301 from the new back to the old but am unsure of the correct route to take that will provide the leat amount of damage to Google serps.

Please advise on the best way to handle this.

[cleanup]

"Would using a 301 redirect on these old links to the new "SE" friendly links be a huge gamble on my Google serps? "

Yes.

[rjwmotor]

what to do?

[jimbeetle]

You should 301 the old urls to the new, there shouldn't be any problem with Google or any other SE. But since the cart is going to allow access to the same pages using the old urls, then you must 301 the old otherwise you'll have dupe pages.

[tedster]

Many people who use a 301 redirect for changing urls have great success. Troubles have been reported by only a small minority, from what I can tell. If the new urls are "the way forward" for you, then I would say redirect the important urls (the ones with inbound links or significant search traffic) and let the others go 404.

Also, change all your existing links on your pages to the new url structure to speed the Google process. You may well get through this change with barely a bump in the road.

[rjwmotor]

"and let the others go 404"

That's the problem. The others will never go 404 as the cart will allow access to both. I'm not as worried about individual product pages b/c I don't have tons of those listed in G anyway; it's the category pages that rank well and would need to be 301'd.

As stated in reply above I "must 301 them b/c of dup penalty" is what I figured.

My host has a built in 301 redirect script. Is this the best(I know it's the easiest) way to go about it or should it be coded in the .htaccess file?

[rjwmotor]

whole new problem...tried to 301 a couple of these with the host supplied 301 and it doesn't work. It's not reading the "?", "&" variables.

Does this mean all would have to be hand coded?

Coding for the "best" 301 would be appreciated!