Would like to upgrade to 5.1 and DTD from prologic

First of all I would like to commend this site on a wealth of information from all of the knowledgeable individuals.
I don't have a system like some of the audiofiles I've read about,but what i have in common with this type of forum is a love of clean musical sound.My system although somewhat
older is a ONKYO TX-SV919THX reciever which is about 6 years old,but it is just prologic(only 4-channels)there lies one of my problems.The speakers i use are def-tech's bp2000's for the mains,I incorporate bose 901's for the rears, my other
problem is i use the equlizer that came with the bose,and a 10 band graphic eq.through the tape monitor loop.the eq's seem to bring the clarity out when in stereo mode but when i use any surruond mode it degrades the sound terribly.The reciever has the ability to imput 5 channels via DB-25 pin connector aka.dolby surround (AC-3format).Is it possible to retain the tonal qualities of the equalization and be able to achieve a true surround image? DTS,SACD ETC.
Some of my equipment include a hi-fy vcr,dvd player and satelite reciever.I KNOW THAT I AM IN NEED OF SOME SERIOUS UPGRADES.can i find a surround processor that will get me in the ballpark or just bite the bullet and find a quality reciever for someone on a budjet. PLEASE HELP YOUR IDEAS AND OR COMMENTS WOULD BE GREATLY APPRECIATED
Just get an older DENNON 3801 it has all the goodies you need 24bit processors dts & ac3 6.1 7.1 and you can get one forI guess $500 or in that neighborhood.

Look for a nice set of matching satellites about $100 to $150 each with center channel. If you are patient and keep your eye out you can probably get them cheaper. A really good 12" self powered sub with about a 250 watts is the key to a great system.

You don't have to get it all at once, but buy good stuff and you will probably not need to do it again.
You can get a cable that is DB-25 at one end with 6 rca's at the other end (monster makes one at about $150). I did this very thing when I had an onkyo unit at one time in the past. You then use the DD/DTS decoders in the DVD player and you are all set for movies. Onkyo made a decoder at one time (you can find them used sometimes for about $50 bucks) but they were only DD with no DTS. You have to use your graphic Eq. in only two of your channels as it is a two channel unit. If you want to use it for your Front L&R channels then it needs to be placed in the chain between your front L&R pre out and amp in (there is a jumper you must remove to do this. Also, the bose Eq. is not the same as a graphic Eq. and is for use with bose 901 model only. If the bose are your rear speakers then it also needs to be placed in the chain so that it will affect only those channels and no others. This would also be your pre out amp in jacks for your rear channels. The tape monitor loop is also a way to go in some cases (but not in yours). In other words, you can put these to Eq's anywhere in the chain that you have pre out amp in jacks as long as they only affect those two channels.
Honestly to me the best upgrade you can do always is front speakers. But if you want to upgrade your processor look to either the Anthem, the Rotel or the Sony ES in my opinion. I have a sony es receiver and use the pre-out to a power amp for the fronts so my 2 channel does not suffer. But again to me you always want to pick speakers first and then mate the rest of your equipment to match up with your front speakers.
Sogood51 I would like to thank you for yhe info.I hooked up the eq's like you said and i could finally enjoy what my surround modes were like.The only problem is that i believe i lost some of the sound depth that i was acustom to with the eq's in stereo mode.Is there any way i could incoperate the equalization for both stereo and surround modes.