15GB isn't too bad, but I'm not sure how 'weak' your network is. For a small migration like that I'd probably either use exp/imp to migrate the data, or if you need 100% uptime, I'd set up the second machine as a standby instance and then failover to it. If you need help with setting up either of these, feel free to ask or email me.
Steve thanks a lot for your information...following are some more points ..so that you have a clear picture...
1. Migration is from SQL2K to Oracle
2. Target oracle DB is geographically seperated
3. 100% uptime is not required we can do the migration on a weekend.
4. What is the idea behind " making the second machiene as a stand by and then failiver it" ? Can you please give more information, articles?
5. How about using DBartisan? Is it the proper tool for this requirement?