If the link is an image include file size for those with slower modems. Realize that a good percentage of visitors will not enter your site from the homepage. Point Links inward especially at the higher levels of your site. You will work hard at attracting visitors to you so don't invite them to leave as soon as they've come in. Give your visitors the opportunity to visit important external links after you've had a chance to tell them about your site.
Frames have their pros and cons.
Frames are especially useful if you wish to keep your navigational links continuously available to the visitor. Having all the links on one page in a frame also makes it easier to make updates to the links since only one page needs editing as opposed to all your pages. The problems with frames are that not all browsers support them. This is particularly important to busy commercial sites where the few percent using these browsers can mean a large number of visitors left out. In these cases alternate non-framed sites are created to support those visitors.