Wah still got ppl use this dead video format
You can Re-encode + resize with WinFF, SUPER or MediaCore (internal stuff are mostly the same.)
But remember re-encode is irreversible proccess, you can have smaller rmvb video but the quality will not be the same anymore.

The development of RMVB stopped 5/6 years ago, the compression efficiency/speed cannot compare with the current standard(H264), plus RMVB have no Dxva/GPGPU support.
ITs still widely used because some ppl dont mind blurry video

Re-encode(stripping away more data) is the only way to reduce the size, trust me.
File archiver like Winzip or 7zip wont help in your case cause RMVB and any video you got from internet, cause they are already heavily compressed, Winzip and 7zip is totally useless for compressed video.
Unless you wanna split them into 700mb so you can burn into muitle CD-R/RW.

This post has been edited by 1024kbps: Sep 8 2011, 06:17 PM